0001104659-13-070680.txt : 20130918 0001104659-13-070680.hdr.sgml : 20130918 20130918100021 ACCESSION NUMBER: 0001104659-13-070680 CONFORMED SUBMISSION TYPE: 485BPOS PUBLIC DOCUMENT COUNT: 8 FILED AS OF DATE: 20130918 DATE AS OF CHANGE: 20130918 EFFECTIVENESS DATE: 20130918 FILER: COMPANY DATA: COMPANY CONFORMED NAME: MFS SERIES TRUST IX /MA/ CENTRAL INDEX KEY: 0000063075 IRS NUMBER: 042535629 STATE OF INCORPORATION: MA FISCAL YEAR END: 0430 FILING VALUES: FORM TYPE: 485BPOS SEC ACT: 1933 Act SEC FILE NUMBER: 002-50409 FILM NUMBER: 131102766 BUSINESS ADDRESS: STREET 1: 111 HUNTINGTON AVENUE STREET 2: 24TH FLOOR CITY: BOSTON STATE: MA ZIP: 02199 BUSINESS PHONE: 18006372929 MAIL ADDRESS: STREET 1: 111 HUNTINGTON AVENUE STREET 2: 24TH FLOOR CITY: BOSTON STATE: MA ZIP: 02199 FORMER COMPANY: FORMER CONFORMED NAME: MFS SERIES TRUST IX DATE OF NAME CHANGE: 19950207 FORMER COMPANY: FORMER CONFORMED NAME: MFS BOND FUND DATE OF NAME CHANGE: 19930408 FORMER COMPANY: FORMER CONFORMED NAME: MFS FIXED INCOME TRUST DATE OF NAME CHANGE: 19920703 FILER: COMPANY DATA: COMPANY CONFORMED NAME: MFS SERIES TRUST IX /MA/ CENTRAL INDEX KEY: 0000063075 IRS NUMBER: 042535629 STATE OF INCORPORATION: MA FISCAL YEAR END: 0430 FILING VALUES: FORM TYPE: 485BPOS SEC ACT: 1940 Act SEC FILE NUMBER: 811-02464 FILM NUMBER: 131102767 BUSINESS ADDRESS: STREET 1: 111 HUNTINGTON AVENUE STREET 2: 24TH FLOOR CITY: BOSTON STATE: MA ZIP: 02199 BUSINESS PHONE: 18006372929 MAIL ADDRESS: STREET 1: 111 HUNTINGTON AVENUE STREET 2: 24TH FLOOR CITY: BOSTON STATE: MA ZIP: 02199 FORMER COMPANY: FORMER CONFORMED NAME: MFS SERIES TRUST IX DATE OF NAME CHANGE: 19950207 FORMER COMPANY: FORMER CONFORMED NAME: MFS BOND FUND DATE OF NAME CHANGE: 19930408 FORMER COMPANY: FORMER CONFORMED NAME: MFS FIXED INCOME TRUST DATE OF NAME CHANGE: 19920703 0000063075 S000002492 MFS Bond Fund C000006711 A MFBFX C000006712 R4 MFBJX C000006716 B MFBBX C000006717 C MFBCX C000006718 I MBDIX C000006720 R1 MFBGX C000006722 R2 MBRRX C000006723 R3 MFBHX C000070424 R5 MFBKX 0000063075 S000002495 MFS Limited Maturity Fund C000006744 I MQLIX C000006745 A MQLFX C000006746 R4 MQLJX C000006747 529A EALMX C000006748 529B EBLMX C000006749 529C ELDCX C000006750 B MQLBX C000006751 C MQLCX C000006753 R1 MQLGX C000006755 R2 MLMRX C000006756 R3 MQLHX C000119776 R5 MQLKX 0000063075 S000002496 MFS Municipal Limited Maturity Fund C000006757 A MTLFX C000006758 B MTLBX C000006759 C MTLCX C000092113 I MTLIX 0000063075 S000002497 MFS Research Bond Fund C000006760 A MRBFX C000006761 R4 MRBJX C000006762 529A EARBX C000006763 529B EBRBX C000006764 529C ECRBX C000006765 B MRBBX C000006766 C MRBCX C000006767 I MRBIX C000006769 R1 MRBGX C000006771 R2 MRRRX C000006772 R3 MRBHX C000034443 R5 MRBKX 485BPOS 1 a13-17727_8485bpos.htm POST-EFFECTIVE AMENDMENT FILED PURSUANT TO SECURITIES ACT RULE 485(B)

 

As filed with the Securities and Exchange Commission on September 18, 2013

 

1933 Act File No. 2-50409

 

1940 Act File No. 811-2464

 

 

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C.  20549

 


 

FORM N-1A

 

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

 

POST-EFFECTIVE AMENDMENT NO. 85

 

AND

 

REGISTRATION STATEMENT

UNDER

THE INVESTMENT COMPANY ACT OF 1940

 

AMENDMENT NO. 78

 

MFS® SERIES TRUST IX

(Exact Name of Registrant as Specified in Charter)

 

111 Huntington Avenue, Boston, Massachusetts 02199-7618

(Address of Principal Executive Offices)

 

Registrant’s Telephone Number, Including Area Code: 617-954-5000

 

Susan S. Newton, Massachusetts Financial Services Company

111 Huntington Avenue, Boston, Massachusetts 02199-7618

(Name and Address of Agent for Service)

 

APPROXIMATE DATE OF PROPOSED PUBLIC OFFERING:

It is proposed that this filing will become effective (check appropriate box)

 

x immediately upon filing pursuant to paragraph (b)

o on [date] pursuant to paragraph (b)

o 60 days after filing pursuant to paragraph (a)(i)

o on [date] pursuant to paragraph (a)(i)

o 75 days after filing pursuant to paragraph (a)(ii)

o on [date] pursuant to paragraph (a)(ii) of rule 485.

 

If appropriate, check the following box:

o this post-effective amendment designates a new effective date for a previously filed post-effective amendment

 

 

 



 

NOTICE

 

Notice is hereby given that this Registration Statement has been executed on behalf of the Registrant by an officer of the Registrant as an officer and not individually, and the obligations of or arising out of this Registration Statement are not binding upon any of the Trustees, officers, or shareholders of the Registrant individually, but are binding only upon the assets and property of the Registrant.

 



 

SIGNATURES

 

Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, the Registrant certifies that it meets all of the requirements for effectiveness of this Registration Statement pursuant to Rule 485(b) under the Securities Act of 1933 and has duly caused this Post-Effective Amendment to the Registration Statement to be signed on its behalf by the undersigned, thereto duly authorized, in the City of Boston and The Commonwealth of Massachusetts on the 18th day of September 2013.

 

 

MFS® SERIES TRUST IX

 

 

 

By:

JOHN M. CORCORAN*

 

Name:

John M. Corcoran

 

Title:

President

 

Pursuant to the requirements of the Securities Act of 1933, this Post-Effective Amendment to its Registration Statement has been signed below by the following persons in the capacities indicated on September 18, 2013.

 

SIGNATURE

 

TITLE

 

 

 

JOHN M. CORCORAN*

 

President (Principal Executive Officer)

John M. Corcoran

 

 

 

 

 

 

 

 

DAVID L. DILORENZO*

 

Principal Financial and Accounting Officer

David L. DiLorenzo

 

 

 

 

 

 

 

 

ROBERT E. BUTLER*

 

Trustee

Robert E. Butler

 

 

 

 

 

 

 

 

MAUREEN R. GOLDFARB*

 

Trustee

Maureen R. Goldfarb

 

 

 

 

 

 

 

 

DAVID H. GUNNING*

 

Trustee

David H. Gunning

 

 

 

 

 

 

 

 

WILLIAM R. GUTOW*

 

Trustee

William R. Gutow

 

 

 

 

 

 

 

 

MICHAEL HEGARTY*

 

Trustee

Michael Hegarty

 

 

 

 

 

 

 

 

JOHN P. KAVANAUGH*

 

Trustee

John P. Kavanaugh

 

 

 



 

ROBERT J. MANNING*

 

Trustee

Robert J. Manning

 

 

 

 

 

 

 

 

J. DALE SHERRATT*

 

Trustee

J. Dale Sherratt

 

 

 

 

 

 

 

 

LAURIE J. THOMSEN*

 

Trustee

Laurie J. Thomsen

 

 

 

 

 

 

 

 

ROBERT W. UEK*

 

Trustee

Robert W. Uek

 

 

 

 

 

 

 

*By:

SUSAN S.NEWTON

 

 

Name:

Susan S. Newton

 

 

 

as Attorney-in-fact

 

 

 

 

 

Executed by Susan S. Newton on behalf of those indicated pursuant to a Power of Attorney, dated December 7, 2012 (Trustees), and a Power of Attorney, dated December 7, 2012 (Corcoran) (DiLorenzo); filed herewith.

 



 

MFS Series Trust I

MFS Series Trust II

MFS Series Trust III

MFS Series Trust IV

MFS Series Trust V

MFS Series Trust VI

MFS Series Trust VII

MFS Series Trust VIII

MFS Series Trust IX

MFS Series Trust X

MFS Series Trust XI

MFS Series Trust XII

MFS Series Trust XIII

MFS Series Trust XIV

MFS Series Trust XV

MFS Series Trust XVI

Massachusetts Investors Growth Stock Fund

Massachusetts Investors Trust

MFS Institutional Trust

MFS Municipal Series Trust

MFS Variable Insurance Trust

MFS Variable Insurance Trust II

MFS Variable Insurance Trust III

MFS California Municipal Fund

MFS Charter Income Trust

MFS Government Markets Income Trust

MFS High Income Municipal Trust

MFS High Yield Municipal Trust

MFS InterMarket Income Trust I

MFS Intermediate High Income Fund

MFS Intermediate Income Trust

MFS Investment Grade Municipal Trust

MFS Multimarket Income Trust

MFS Municipal Income Trust

MFS Special Value Trust

 

(each a “Registrant”)

 

POWER OF ATTORNEY

 

The undersigned, a Trustee of each of the above-mentioned Registrants, hereby severally constitutes and appoints Mark N. Polebaum, Susan S. Newton,

 



 

Christopher R. Bohane, Thomas H. Connors, Brian E. Langenfeld and Susan A. Pereira, and each of them singly, as true and lawful attorneys, with full power to them and each of them to sign for each of the undersigned, in the names of, and in the capacities indicated below, any Registration Statement and any and all amendments thereto and to file the same with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission for the purpose of registering the Registrant as a management investment company under the Investment Company Act of 1940 and/or the shares issued by the Registrant under the Securities Act of 1933 granting unto my said attorneys, and each of them, acting alone, full power and authority to do and perform each and every act and thing requisite or necessary or desirable to be done in the premises, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorneys or any of them may lawfully do or cause to be done by virtue thereof.

 

IN WITNESS WHEREOF, the undersigned have hereunto set their hand on this 7th day of December, 2012.

 

ROBERT E. BUTLER

 

Trustee

Robert E. Butler

 

 

 

 

 

 

 

 

MAUREEN R. GOLDFARB

 

Trustee

Maureen R. Goldfarb

 

 

 

 

 

 

 

 

DAVID H. GUNNING

 

Trustee

David H. Gunning

 

 

 

 

 

 

 

 

WILLIAM R. GUTOW

 

Trustee

William R. Gutow

 

 

 

 

 

 

 

 

MICHAEL HEGARTY

 

Trustee

Michael Hegarty

 

 

 

 

 

 

 

 

JOHN P. KAVANAUGH

 

Trustee

John P. Kavanaugh

 

 

 



 

ROBERT J. MANNING

 

Trustee

Robert J. Manning

 

 

 

 

 

 

 

 

J. DALE SHERRATT

 

Trustee

J. Dale Sherratt

 

 

 

 

 

 

 

 

LAURIE J. THOMSEN

 

Trustee

Laurie J. Thomsen

 

 

 

 

 

 

 

 

ROBERT W. UEK

 

Trustee

Robert W. Uek

 

 

 



 

MFS Series Trust I

MFS Series Trust II

MFS Series Trust III

MFS Series Trust IV

MFS Series Trust V

MFS Series Trust VI

MFS Series Trust VII

MFS Series Trust VIII

MFS Series Trust IX

MFS Series Trust X

MFS Series Trust XI

MFS Series Trust XII

MFS Series Trust XIII

MFS Series Trust XIV

MFS Series Trust XV

MFS Series Trust XVI

Massachusetts Investors Growth Stock Fund

Massachusetts Investors Trust

MFS Institutional Trust

MFS Municipal Series Trust

MFS Variable Insurance Trust

MFS Variable Insurance Trust II

MFS Variable Insurance Trust III

MFS California Municipal Fund

MFS Charter Income Trust

MFS Government Markets Income Trust

MFS High Income Municipal Trust

MFS High Yield Municipal Trust

MFS InterMarket Income Trust I

MFS Intermediate High Income Fund

MFS Intermediate Income Trust

MFS Investment Grade Municipal Trust

MFS Multimarket Income Trust

MFS Municipal Income Trust

MFS Special Value Trust

 

(each a “Registrant”)

 

POWER OF ATTORNEY

 

The undersigned, being the President and Principal Executive Officer, and Treasurer and Principal Financial and Accounting Officer, respectively, of each of the above-mentioned Registrants, hereby severally constitutes and appoints Mark N. Polebaum, Susan S. Newton, Christopher R. Bohane, Thomas H. Connors, Brian E.

 



 

Langenfeld and Susan A. Pereira, and each of them singly, as true and lawful attorneys, with full power to them and each of them to sign for each of the undersigned, in the names of, and in the capacities indicated below, any Registration Statement and any and all amendments thereto and to file the same with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission for the purpose of registering the Registrant as a management investment company under the Investment Company Act of 1940 and/or the shares issued by the Registrant under the Securities Act of 1933 granting unto my said attorneys, and each of them, acting alone, full power and authority to do and perform each and every act and thing requisite or necessary or desirable to be done in the premises, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorneys or any of them may lawfully do or cause to be done by virtue thereof.

 

IN WITNESS WHEREOF, the undersigned have hereunto set their hand on this 7th day of December, 2012.

 

 

JOHN M. CORCORAN

 

President (Principal Executive Officer)

John M. Corcoran

 

 

 

 

 

 

 

 

DAVID L. DILORENZO

 

Principal Financial and Accounting Officer

David L. DiLorenzo

 

 

 



 

MFS SERIES TRUST IX

 

On behalf of

 

MFS® BOND FUND

MFS® LIMITED MATURITY FUND

MFS® MUNICIPAL LIMITED MATURITY FUND

MFS® RESEARCH BOND FUND

 

INDEX TO EXHIBITS

 

EXHIBIT NO.

 

DESCRIPTION OF EXHIBIT

 

PAGE NO.

 

 

 

 

 

101

 

Risk/Return summary of each fund’s prospectus as an Interactive Data File using eXtensible Business Reporting Language (“XBRL”)

 

 

 


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2013-04-30 2013-04-30 0000063075 ck0000063075:S000002497Member ck0000063075:C000034443Member 2013-04-30 2013-04-30 0000063075 ck0000063075:S000002497Member rr:AfterTaxesOnDistributionsMember ck0000063075:C000006760Member 2013-04-30 2013-04-30 0000063075 ck0000063075:S000002497Member rr:AfterTaxesOnDistributionsAndSalesMember ck0000063075:C000006760Member 2013-04-30 2013-04-30 0000063075 ck0000063075:S000002497Member ck0000063075:index_Barclays_US_Aggregate_Bond_IndexMember 2013-04-30 2013-04-30 iso4217:USD xbrli:pure On shares purchased without an initial sales charge and redeemed within 18 months of purchase for shares purchased on or after August 1, 2012, and within 24 months of purchase for shares purchased prior to August 1, 2012. MFS Fund Distributors, Inc. has agreed in writing to waive the Class A service fee and the Class 529A service fee to 0.15% of the fund's average daily net assets annually until modified by the fund's Board of Trustees, but such agreement will continue until at least August 31, 2014. For one year from the date of purchase of Class B and Class 529B shares, assets attributable to such Class B and Class 529B shares are subject to the Class B and Class 529B service fee of 0.25% of the fund's average daily net assets annually. On assets attributable to all other Class B and Class 529B shares, MFS Fund Distributors, Inc. has agreed in writing to waive the Class B and Class 529B service fee to 0.15% of the fund's average daily net assets annually until modified by the fund's Board of Trustees, but such agreement will continue until at least August 31, 2014. Also, MFS Fund Distributors, Inc. has agreed in writing to waive the Class R2 distribution fee to 0.15% of the fund's average daily net assets annually until modified by the fund's Board of Trustees, but such agreement will continue until at least August 31, 2014. In addition, MFS Fund Distributors, Inc. has agreed in writing to waive the program management fee for each of the fund's Class 529A, Class 529B, and Class 529C shares to 0.05% of the fund's average daily net assets attributable to each share class annually. This written agreement will expire on August 31, 2014, unless MFS Fund Distributors, Inc. elects to extend the waiver. MFS Fund Distributors, Inc., has agreed in writing to waive the Class A service fee to 0.15% of the fund's average daily net assets annually until modified by the fund's Board of Trustees, but such agreement will continue until at least August 31, 2014. In addition, for one year from the date of purchase of Class B shares, assets attributable to such Class B shares are subject to the Class B service fee of 0.25% of the fund's average daily net assets annually. On assets attributable to all other Class B shares, MFS Fund Distributors, Inc., has agreed in writing to waive the Class B service fee to 0.15% of the fund's average daily net assets annually until modified by the fund's Board of Trustees, but such agreement will continue until at least August 31, 2014. In addition, Massachusetts Financial Services Company has agreed in writing to bear the fund's expenses, excluding management fees, distribution and service fees, interest, taxes, extraordinary expenses, brokerage and transaction costs, and investment-related expenses (such as interest and borrowing expenses incurred in connection with the fund's investment activity), such that "Other Expenses" do not exceed 0.15% of the fund's average daily net assets annually for each class of shares. This written agreement will continue until modified by the fund's Board of Trustees, but such agreement will continue until at least August 31, 2014. MFS Fund Distributors, Inc., has agreed in writing to waive the Class A and Class 529A service fee to 0.15% of the fund's average daily net assets annually until modified by a vote of the fund's Board of Trustees, but such agreement will continue until at least August 31, 2014. Assets attributable to Class B shares purchased prior to May 1, 2006, are subject to the Class B service fee of 0.25% of the fund's average daily net assets annually. On assets attributable to all other Class B shares, MFS Fund Distributors, Inc., has agreed in writing to waive the Class B service fee to 0.15% of the fund's average daily net assets annually until modified by the fund's Board of Trustees, but such agreement will continue until at least August 31, 2014. MFS Fund Distributors, Inc., has agreed in writing to waive the program management fee for each of the fund's Class 529A, Class 529B, and Class 529C shares to 0.05% of the fund's average daily net assets attributable to each share class annually. This written agreement will expire on August 31, 2014, unless MFS Fund Distributors, Inc. elects to extend the waiver. MFS SERIES TRUST IX /MA/ 485BPOS false 0000063075 2013-04-30 2013-08-27 2013-08-28 2013-08-28 MFS&#174; Bond Fund - Summary of Key Information MFBFX MFBJX MFBBX MFBCX MBDIX MFBGX MBRRX MFBHX MFBKX Principal Risks <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The principal risks of investing in the fund are:</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Interest Rate Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;The price of a debt instrument falls when interest rates rise and rises when interest rates fall. Instruments with longer maturities, or that do not pay current interest, are more sensitive to interest rate changes.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Credit Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;The price of a debt instrument depends, in part, on the credit quality of the issuer, borrower, counterparty, or underlying collateral or assets and the terms of the instrument. The price of a debt instrument can decline in response to changes in the financial condition of the issuer, borrower, counterparty, or underlying collateral or assets, or changes in specific or general market, economic, industry, political, regulatory, geopolitical, and other conditions.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">Lower quality debt instruments (commonly referred to as &#8220;high yield securities&#8221; or &#8220;junk bonds&#8221;) can involve a substantially greater risk of default or can already be in default, and their values can decline significantly. Lower quality debt instruments are regarded as having predominantly speculative characteristics. 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Emerging markets can have less developed markets, greater custody and operational risk, less developed legal, regulatory, and accounting systems, and greater political, social, and economic instability than developed markets.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Currency Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;The value of foreign currencies relative to the U.S. dollar fluctuates in response to market, economic, industry, political, regulatory, geopolitical, and other conditions, and a decline in the value of a foreign currency versus the U.S. dollar reduces the value in U.S. dollars of investments denominated in that foreign currency.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Prepayment/Extension Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;Instruments subject to prepayment and/or extension can reduce the potential for gain for the instrument&#8217;s holders if the instrument is prepaid and increase the potential for loss if the maturity of the instrument is extended.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Inflation-Adjusted Debt Instruments Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;Interest payments on inflation-adjusted debt instruments can be unpredictable and vary based on the level of inflation. If inflation is negative, principal and income can both decline.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Municipal Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;The price of a municipal instrument can be volatile and significantly affected by adverse tax or court rulings, legislative or political changes, changes in specific or general market and economic conditions, and the financial condition of municipal issuers and insurers. Because many municipal instruments are issued to finance similar projects, conditions in these industries can significantly affect the fund and the overall municipal market.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Derivatives Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;Derivatives can be highly volatile and involve risks in addition to the risks of the underlying indicator(s)&#160;on which the derivative is based. Gains or losses from derivatives can be substantially greater than the derivatives&#8217; original cost.&#160; Derivatives can involve leverage.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Leveraging Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;Leverage involves investment exposure in an amount exceeding the initial investment. Leverage can cause increased volatility by magnifying gains or losses.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Liquidity Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;It may not be possible to sell certain investments, types of investments, and/or segments of the market at any particular time or at an acceptable price.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Counterparty and Third Party Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;Transactions involving a counterparty or third party other than the issuer of the instrument are subject to the credit risk of the counterparty or third party, and to the counterparty&#8217;s or third party&#8217;s ability to perform in accordance with the terms of the transaction.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Investment Selection Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;MFS&#8217; investment analysis and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests.</font> </p> As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Example <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">This example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The example assumes that: you invest $10,000 in the fund for the time periods indicated and you redeem your shares at the end of the time periods (unless otherwise indicated); your investment has a 5% return each year; and the fund&#8217;s operating expenses remain the same.</font> </p> 556 727 914 1452 561 799 1060 1677 161 499 860 1677 261 499 860 1878 161 499 860 1878 59 186 324 726 161 499 860 1878 110 343 595 1317 85 265 460 1025 59 186 324 726 49 154 269 604 ~ http://mfs.com/20130827/role/ScheduleExpenseExampleTransposed20003 column dei_LegalEntityAxis compact ck0000063075_S000002492Member row primary compact * ~ ~ http://mfs.com/20130827/role/ScheduleExpenseExampleNoRedemptionTransposed20004 column dei_LegalEntityAxis compact ck0000063075_S000002492Member row primary compact * ~ Although your actual costs will likely be higher or lower, under these assumptions your costs would be: Performance Information <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund&#8217;s performance over time and how the fund&#8217;s performance over time compares with that of a broad measure of market performance.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The fund&#8217;s past performance (before and after taxes) does not necessarily indicate how the fund will perform in the future. Updated performance is available online at <b>mfs.com</b> or by calling 1-800-225-2606.</font> </p> Class A Bar Chart. 0.0946 0.0607 0.0171 0.0493 0.0351 -0.0998 0.2837 0.1122 0.0640 0.1044 ~ http://mfs.com/20130827/role/ScheduleAnnualTotalReturnsBarChart20005 column dei_LegalEntityAxis compact ck0000063075_S000002492Member column rr_ProspectusShareClassAxis compact ck0000063075_C000006711Member row primary compact * ~ <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The bar chart does not take into account any sales charges (loads) that you may be required to pay upon purchase or redemption of the fund's shares. If these sales charges were included, they would reduce the returns shown.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-family: Times New Roman;"/> </p> highest quarterly return 0.1130 2009-06-30 lowest quarterly return -0.0518 2008-09-30 The total return for the six-month period ended -0.0272 2013-06-30 <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The total return for the six-month period ended June&#160;30, 2013 was (2.72)%. During the period(s)&#160;shown in the bar chart, the highest quarterly return was 11.30% (for the calendar quarter ended June&#160;30, 2009) and the lowest quarterly return was (5.18)% (for the calendar quarter ended September&#160;30, 2008).</font> </p> Performance Table. 0.0564 0.0753 0.0624 Returns Before Taxes B Shares 0.0865 0.0783 0.0609 Returns Before Taxes C Shares 0.1072 0.0888 0.0713 Returns Before Taxes I Shares 0.0965 0.0783 0.0600 Returns Before Taxes R1 Shares 0.1017 0.0836 0.0650 Returns Before Taxes R2 Shares 0.1044 0.0861 0.0679 Returns Before Taxes R3 Shares 0.1071 0.0888 0.0709 Returns Before Taxes R4 Shares 0.1076 0.0889 0.0714 Returns Before Taxes R5 Shares 0.0520 0.0754 0.0632 Returns Before Taxes A Shares 0.0365 0.0555 0.0433 Returns After Taxes on Distributions A Shares 0.0334 0.0525 0.0420 Returns After Taxes on Distributions and Sale of Fund Shares A Shares 0.0937 0.0765 0.0623 Index Comparison (Reflects no deduction for fees, expenses or taxes) Barclays U.S. Credit Bond Index ~ http://mfs.com/20130827/role/ScheduleAverageAnnualReturnsTransposed20006 column dei_LegalEntityAxis compact ck0000063075_S000002492Member column rr_PerformanceMeasureAxis compact * row primary compact * ~ <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">Aft</font><font size="2" style="font-size:10.0pt; font-family: Times New Roman;">er-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Your actual after-tax returns will depend on your own tax situation, and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k)&#160;plans or individual retirement accounts. The after-tax returns are shown for only one of the fund&#8217;s classes of shares, and after-tax returns for the fund&#8217;s other classes of shares will vary from the returns shown.</font> </p> mfs.com Average Annual Total Returns (for the Periods Ended December 31, 2012) The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund's performance over time and how the fund's performance over time compares with that of a broad measure of market performance. Your actual after-tax returns will depend on your own tax situation, and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. The bar chart does not take into account any sales charges (loads) that you may be required to pay upon purchase or redemption of the fund's shares. If these sales charges were included, they would reduce the returns shown. The after-tax returns are shown for only one of the fund's classes of shares, and after-tax returns for the fund's other classes of shares will vary from the returns shown. 1-800-225-2606 (Reflects no deduction for fees, expenses or taxes) After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. The fund's past performance (before and after taxes) does not necessarily indicate how the fund will perform in the future. Fees and Expenses <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">This table describes the fees and expenses that you may pay when you buy and hold shares of the fund.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">You may qualify for sales charge reductions if you and certain members of your family invest, or agree to invest in the future, at least $50,000 in MFS Funds. More information about these and other waivers and reductions is available from your financial intermediary and in &#8220;Sales Charges and Waivers or Reductions&#8221; on page&#160;8 of the fund&#8217;s prospectus and &#8220;Waivers of Sales Charges&#8221; on page&#160;H-1 of the fund&#8217;s Statement of Additional Information (&#8220;SAI&#8221;).</font> </p> 0.0475 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0100 0.0400 0.0100 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0038 0.0038 0.0038 0.0038 0.0038 0.0038 0.0038 0.0038 0.0038 0.0025 0.0100 0.0100 0.0000 0.0100 0.0050 0.0025 0.0000 0.0000 0.0020 0.0020 0.0020 0.0020 0.0020 0.0020 0.0020 0.0020 0.0010 0.0083 0.0158 0.0158 0.0058 0.0158 0.0108 0.0083 0.0058 0.0048 ~ http://mfs.com/20130827/role/ScheduleShareholderFees20001 column dei_LegalEntityAxis compact ck0000063075_S000002492Member row primary compact * ~ ~ http://mfs.com/20130827/role/ScheduleAnnualFundOperatingExpenses20002 column dei_LegalEntityAxis compact ck0000063075_S000002492Member row primary compact * ~ You may qualify for sales charge reductions if you and certain members of your family invest, or agree to invest in the future, at least $50,000 in MFS Funds. Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): Shareholder Fees (fees paid directly from your investment): On shares purchased without an initial sales charge and redeemed within 18 months of purchase for shares purchased on or after August 1, 2012, and within 24 months of purchase for shares purchased prior to August 1, 2012. 50000 Portfolio Turnover <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The fund pays transaction costs, such as commissions, when it buys and sells securities (or &#8220;turns over&#8221; its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These transaction costs, which are not reflected in &#8220;Annual Fund Operating Expenses&#8221; or in the &#8220;Example,&#8221; affect the fund&#8217;s performance.&#160; During the most recent fiscal year, the fund&#8217;s portfolio turnover rate was 47% of the average value of its portfolio.</font> </p> 0.47 Principal Investment Strategies <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">MFS (Massachusetts Financial Services Company, the fund&#8217;s investment adviser) normally invests at least 80% of the fund&#8217;s net assets in debt instruments.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">MFS invests the majority of the fund&#8217;s assets in corporate debt instruments, but may also invest in other types of debt instruments.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">MFS primarily invests the fund&#8217;s assets in investment grade debt instruments, but may also invest in less than investment grade quality debt instruments (lower quality debt instruments).</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">MFS may invest the fund&#8217;s assets in foreign securities, including emerging market securities.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">While MFS may use derivatives for any investment purpose, to the extent MFS uses derivatives, MFS expects to use derivatives primarily to increase or decrease exposure to a particular market, segment of the market, or security, to increase or decrease interest rate or currency exposure, or as alternatives to direct investments. Derivatives include futures, forward contracts, options, structured securities, inverse floating rate instruments, and swaps.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">MFS uses a bottom-up investment approach to buying and selling investments for the fund. Investments are selected primarily based on fundamental analysis of individual instruments and their issuers. Quantitative models that systematically evaluate instruments may also be considered. In structuring the fund, MFS may also consider top-down factors.</font> </p> Investment Objective <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The fund&#8217;s investment objective is to seek total return with an emphasis on current income, but also considering capital appreciation.</font> </p> MFS&#174; Limited Maturity Fund - Summary of Key Information MQLIX MQLFX MQLJX EALMX EBLMX ELDCX MQLBX MQLCX MQLGX MLMRX MQLHX MQLKX Principal Risks <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The principal risks of investing in the fund are:</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Interest Rate Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;The price of a debt instrument falls when interest rates rise and rises when interest rates fall. Instruments with longer maturities, or that do not pay current interest, are more sensitive to interest rate changes.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Credit Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;The price of a debt instrument depends, in part, on the credit quality of the issuer, borrower, counterparty, or underlying collateral or assets and the terms of the instrument. The price of a debt instrument can decline in response to changes in the financial condition of the issuer, borrower, counterparty, or underlying collateral or assets, or changes in specific or general market, economic, industry, political, regulatory, geopolitical, and other conditions.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Foreign Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;Exposure to foreign markets through issuers can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, and other conditions. These factors can make foreign investments, especially those in emerging markets, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Geographic Concentration Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The fund&#8217;s performance could be closely tied to the market, currency, economic, political, regulatory, geopolitical, and other conditions in the countries or regions in which the fund invests and could be more volatile than the performance of more geographically-diversified funds.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Prepayment/Extension Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;Instruments subject to prepayment and/or extension can reduce the potential for gain for the instrument&#8217;s holders if the instrument is prepaid and increase the potential for loss if the maturity of the instrument is extended.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Inflation-Adjusted Debt Instruments Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;Interest payments on inflation-adjusted debt instruments can be unpredictable and vary based on the level of inflation. If inflation is negative, principal and income can both decline.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Municipal Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;The price of a municipal instrument can be volatile and significantly affected by adverse tax or court rulings, legislative or political changes, changes in specific or general market and economic conditions, and the financial condition of municipal issuers and insurers. Because many municipal instruments are issued to finance similar projects, conditions in these industries can significantly affect the fund and the overall municipal market.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Derivatives Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;Derivatives can be highly volatile and involve risks in addition to the risks of the underlying indicator(s)&#160;on which the derivative is based. Gains or losses from derivatives can be substantially greater than the derivatives&#8217; original cost.&#160; Derivatives can involve leverage.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Leveraging Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;Leverage involves investment exposure in an amount exceeding the initial investment. 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An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Example <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">This example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The example assumes that: you invest $10,000 in the fund for the time periods indicated and you redeem your shares at the end of the time periods (unless otherwise indicated); your investment has a 5% return each year; and the fund&#8217;s operating expenses remain the same.</font> </p> 325 505 700 1264 553 795 1061 1691 153 495 861 1691 263 505 871 1900 163 505 871 1900 61 192 335 750 330 531 748 1374 559 822 1110 1798 159 522 910 1798 268 531 918 2004 168 531 918 2004 163 505 871 1900 102 340 597 1331 87 271 471 1049 61 192 335 750 54 170 296 665 ~ http://mfs.com/20130827/role/ScheduleExpenseExampleTransposed20011 column dei_LegalEntityAxis compact ck0000063075_S000002495Member row primary compact * ~ ~ http://mfs.com/20130827/role/ScheduleExpenseExampleNoRedemptionTransposed20012 column dei_LegalEntityAxis compact ck0000063075_S000002495Member row primary compact * ~ Although your actual costs will likely be higher or lower, under these assumptions your costs would be: Performance Information <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund&#8217;s performance over time and how the fund&#8217;s performance over time compares with that of a broad measure of market performance.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The fund&#8217;s past performance (before and after taxes) does not necessarily indicate how the fund will perform in the future. Updated performance is available online at <b>mfs.com</b> or by calling 1-800-225-2606.</font> </p> Class A Bar Chart. 0.0310 0.0165 0.0157 0.0458 0.0400 -0.0424 0.1125 0.0393 0.0122 0.0349 ~ http://mfs.com/20130827/role/ScheduleAnnualTotalReturnsBarChart20013 column dei_LegalEntityAxis compact ck0000063075_S000002495Member column rr_ProspectusShareClassAxis compact ck0000063075_C000006745Member row primary compact * ~ <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The bar chart does not take into account any sales charges (loads) that you may be required to pay upon purchase or redemption of the fund's shares. If these sales charges were included, they would reduce the returns shown.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-family: Times New Roman;"/> </p> highest quarterly return 0.0442 2009-06-30 lowest quarterly return -0.0302 2008-12-31 The total return for the 6-month period ended -0.0022 2013-06-30 <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The total return for the 6-month period ended June&#160;30, 2013 was (0.22)%. During the period(s)&#160;shown in the bar chart, the highest quarterly return was 4.42% (for the calendar quarter ended June&#160;30, 2009) and the lowest quarterly return was (3.02)% (for the calendar quarter ended December&#160;31, 2008).</font> </p> Performance Table. -0.0111 0.0191 0.0237 Returns Before Taxes B Shares 0.0178 0.0214 0.0213 Returns Before Taxes C Shares 0.0365 0.0316 0.0316 Returns Before Taxes I Shares 0.0085 0.0237 0.0250 Returns Before Taxes 529A Shares -0.0118 0.0181 0.0219 Returns Before Taxes 529B Shares 0.0156 0.0204 0.0197 Returns Before Taxes 529C Shares 0.0262 0.0213 0.0205 Returns Before Taxes R1 Shares 0.0323 0.0275 0.0263 Returns Before Taxes R2 Shares 0.0356 0.0290 0.0281 Returns Before Taxes R3 Shares 0.0364 0.0316 0.0309 Returns Before Taxes R4 Shares 0.0382 0.0319 0.0317 Returns Before Taxes R5 Shares 0.0090 0.0249 0.0273 Returns Before Taxes A Shares -0.0002 0.0119 0.0128 Returns After Taxes on Distributions A Shares 0.0058 0.0136 0.0146 Returns After Taxes on Distributions and Sale of Fund Shares A Shares 0.0126 0.0288 0.0313 Index Comparison (Reflects no deduction for fees, expenses or taxes) Barclays 1-3 Year U.S. Government/Credit Bond Index ~ http://mfs.com/20130827/role/ScheduleAverageAnnualReturnsTransposed20014 column dei_LegalEntityAxis compact ck0000063075_S000002495Member column rr_PerformanceMeasureAxis compact * row primary compact * ~ <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">Aft</font><font size="2" style="font-size:10.0pt; font-family: Times New Roman;">er-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Your actual after-tax returns will depend on your own tax situation, and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k)&#160;plans or individual retirement accounts. The after-tax returns are shown for only one of the fund&#8217;s classes of shares, and after-tax returns for the fund&#8217;s other classes of shares will vary from the returns shown.</font> </p> mfs.com The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund's performance over time and how the fund's performance over time compares with that of a broad measure of market performance. Average Annual Total Returns (for the Periods Ended December 31, 2012) Your actual after-tax returns will depend on your own tax situation, and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. The bar chart does not take into account any sales charges (loads) that you may be required to pay upon purchase or redemption of the fund's shares. If these sales charges were included, they would reduce the returns shown. The after-tax returns are shown for only one of the fund's classes of shares, and after-tax returns for the fund's other classes of shares will vary from the returns shown. 1-800-225-2606 (Reflects no deduction for fees, expenses or taxes) The fund's past performance (before and after taxes) does not necessarily indicate how the fund will perform in the future. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Fees and Expenses <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">This table describes the fees and expenses that you may pay when you buy and hold shares of the fund.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">You may qualify for sales charge reductions if you and certain members of your family invest, or agree to invest in the future, at least $50,000 in MFS Funds. More information about these and other waivers and reductions is available from your financial intermediary and in &#8220;Sales Charges and Waivers or Reductions&#8221; on page&#160;9 of the fund&#8217;s prospectus and &#8220;Waivers of Sales Charges&#8221; on page&#160;H-1 of the fund&#8217;s Statement of Additional Information (&#8220;SAI&#8221;).</font> </p> 0.0250 0.0000 0.0000 0.0000 0.0250 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0100 0.0400 0.0100 0.0000 0.0000 0.0400 0.0100 0.0000 0.0000 0.0000 0.0000 0.0000 0.0040 0.0040 0.0040 0.0040 0.0040 0.0040 0.0040 0.0040 0.0040 0.0040 0.0040 0.0040 0.0025 0.0100 0.0100 0.0000 0.0025 0.0100 0.0100 0.0100 0.0050 0.0025 0.0000 0.0000 0.0020 0.0020 0.0020 0.0020 0.0030 0.0030 0.0030 0.0020 0.0020 0.0020 0.0020 0.0013 0.0085 0.0160 0.0160 0.0060 0.0095 0.0170 0.0170 0.0160 0.0110 0.0085 0.0060 0.0053 -0.0010 -0.0010 0.0000 0.0000 -0.0015 -0.0014 -0.0005 0.0000 -0.0010 0.0000 0.0000 0.0000 0.0075 0.0150 0.0160 0.0060 0.0080 0.0156 0.0165 0.0160 0.0100 0.0085 0.0060 0.0053 ~ http://mfs.com/20130827/role/ScheduleShareholderFees20009 column dei_LegalEntityAxis compact ck0000063075_S000002495Member row primary compact * ~ ~ http://mfs.com/20130827/role/ScheduleAnnualFundOperatingExpenses20010 column dei_LegalEntityAxis compact ck0000063075_S000002495Member row primary compact * ~ You may qualify for sales charge reductions if you and certain members of your family invest, or agree to invest in the future, at least $50,000 in MFS Funds. Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): On shares purchased without an initial sales charge and redeemed within 18 months of purchase for shares purchased on or after August 1, 2012, and within 24 months of purchase for shares purchased prior to August 1, 2012. Shareholder Fees (fees paid directly from your investment): 2014-08-31 2014-08-31 2014-08-31 2014-08-31 2014-08-31 2014-08-31 50000 Portfolio Turnover <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The fund pays transaction costs, such as commissions, when it buys and sells securities (or &#8220;turns over&#8221; its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These transaction costs, which are not reflected in &#8220;Annual Fund Operating Expenses&#8221; or in the &#8220;Example,&#8221; affect the fund&#8217;s performance.&#160; During the most recent fiscal year, the fund&#8217;s portfolio turnover rate was 34% of the average value of its portfolio.</font> </p> 0.34 Principal Investment Strategies <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">MFS (Massachusetts Financial Services Company, the fund&#8217;s investment adviser) normally invests the fund&#8217;s assets primarily in debt instruments. Debt instruments include corporate bonds, U.S. Government securities, asset-backed securities, municipal instruments, foreign government securities, inflation-adjusted bonds, and other obligations to repay money borrowed.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The fund&#8217;s dollar-weighted average effective maturity will normally not exceed five years.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">MFS generally invests substantially all of the fund&#8217;s assets in investment grade debt instruments.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">MFS invests the fund&#8217;s assets in U.S. securities and U.S. dollar-denominated foreign securities.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">MFS may invest a large percentage of the fund&#8217;s assets in issuers in a single country, a small number of countries, or a particular geographic region.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">While MFS may use derivatives for any investment purpose, to the extent MFS uses derivatives, MFS expects to use derivatives primarily to increase or decrease exposure to a particular market, segment of the market, or security, to increase or decrease interest rate exposure, or as alternatives to direct investments. Derivatives include futures, forward contracts, options, structured securities, inverse floating rate instruments, and swaps.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">MFS uses a bottom-up investment approach to buying and selling investments for the fund. Investments are selected primarily based on fundamental analysis of individual instruments and their issuers. Quantitative models that systematically evaluate instruments may also be considered. In structuring the fund, MFS may also consider top-down factors.</font> </p> Investment Objective <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The fund&#8217;s investment objective is to seek total return with an emphasis on current income, but also considering capital preservation.</font> </p> MFS&#174; Municipal Limited Maturity Fund - Summary of Key Information MTLFX MTLBX MTLCX MTLIX Principal Risks <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The principal risks of investing in the fund are:</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Interest Rate Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;The price of a debt instrument falls when interest rates rise and rises when interest rates fall. Instruments with longer maturities, or that do not pay current interest, are more sensitive to interest rate changes.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Credit Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;The price of a debt instrument depends, in part, on the credit quality of the issuer, borrower, counterparty, or underlying collateral or assets and the terms of the instrument. The price of a debt instrument can decline in response to changes in the financial condition of the issuer, borrower, counterparty, or underlying collateral or assets, or changes in specific or general market, economic, industry, political, regulatory, geopolitical, and other conditions.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The credit quality of, and the ability to pay principal and interest when due by, an issuer of a municipal instrument depends on the credit quality of the entity supporting the municipal instrument, how essential any services supported by the municipal instrument are, the sufficiency of any revenues or taxes that support the municipal instrument, and/or the willingness or ability of the appropriate government entity to approve any appropriations necessary to support the municipal instrument.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Municipal Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;The price of a municipal instrument can be volatile and significantly affected by adverse tax or court rulings, legislative or political changes, changes in specific or general market and economic conditions, and the financial condition of municipal issuers and insurers. Because many municipal instruments are issued to finance similar projects, conditions in these industries can significantly affect the fund and the overall municipal market.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Prepayment/Extension Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;Instruments subject to prepayment and/or extension can reduce the potential for gain for the instrument&#8217;s holders if the instrument is prepaid and increase the potential for loss if the maturity of the instrument is extended.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Derivatives Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;Derivatives can be highly volatile and involve risks in addition to the risks of the underlying indicator(s)&#160;on which the derivative is based. Gains or losses from derivatives can be substantially greater than the derivatives&#8217; original cost.&#160; Derivatives can involve leverage.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Leveraging Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;Leverage involves investment exposure in an amount exceeding the initial investment. Leverage can cause increased volatility by magnifying gains or losses.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Liquidity Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;It may not be possible to sell certain investments, types of investments, and/or segments of the market at any particular time or at an acceptable price.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Counterparty and Third Party Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;Transactions involving a counterparty or third party other than the issuer of the instrument are subject to the credit risk of the counterparty or third party, and to the counterparty&#8217;s or third party&#8217;s ability to perform in accordance with the terms of the transaction.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <b><font size="2" style="font-size:10.0pt;font-weight:bold; font-family: Times New Roman;">Investment Selection Risk:</font></b> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">&#160;MFS&#8217; investment analysis and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests.</font> </p> As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Example <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">This example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The example assumes that: you invest $10,000 in the fund for the time periods indicated and you redeem your shares at the end of the time periods (unless otherwise indicated); your investment has a 5% return each year; and the fund&#8217;s operating expenses remain the same.</font> </p> 320 491 678 1217 548 782 1040 1645 148 482 840 1645 258 492 849 1856 158 492 849 1856 56 178 312 701 ~ http://mfs.com/20130827/role/ScheduleExpenseExampleTransposed20019 column dei_LegalEntityAxis compact ck0000063075_S000002496Member row primary compact * ~ ~ http://mfs.com/20130827/role/ScheduleExpenseExampleNoRedemptionTransposed20020 column dei_LegalEntityAxis compact ck0000063075_S000002496Member row primary compact * ~ Although your actual costs will likely be higher or lower, under these assumptions your costs would be: Performance Information <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund&#8217;s performance over time and how the fund&#8217;s performance over time compares with that of a broad measure of market performance and one or more other measures of performance for markets in which the fund may invest.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The fund&#8217;s past performance (before and after taxes) does not necessarily indicate how the fund will perform in the future. Updated performance is available online at <b>mfs.com</b> or by calling 1-800-225-2606.</font> </p> Class A Bar Chart. 0.0349 0.0144 0.0139 0.0319 0.0326 0.0095 0.0829 0.0260 0.0603 0.0305 ~ http://mfs.com/20130827/role/ScheduleAnnualTotalReturnsBarChart20021 column dei_LegalEntityAxis compact ck0000063075_S000002496Member column rr_ProspectusShareClassAxis compact ck0000063075_C000006757Member row primary compact * ~ <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The bar chart does not take into account any sales charges (loads) that you may be required to pay upon purchase or redemption of the fund's shares. If these sales charges were included, they would reduce the returns shown.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-family: Times New Roman;"/> </p> highest quarterly return 0.0376 2009-09-30 lowest quarterly return -0.0170 2004-06-30 The total return for the six-month period ended -0.0147 2013-06-30 <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The total return for the six-month period ended June&#160;30, 2013 was (1.47)%. During the period(s)&#160;shown in the bar chart, the highest quarterly return was 3.76% (for the calendar quarter ended September&#160;30, 2009) and the lowest quarterly return was (1.70)% (for the calendar quarter ended June&#160;30, 2004).</font> </p> Performance Table. -0.0159 0.0306 0.0273 Returns Before Taxes B Shares 0.0130 0.0329 0.0249 Returns Before Taxes C Shares 0.0333 0.0430 0.0350 Returns Before Taxes I Shares 0.0048 0.0363 0.0309 Returns Before Taxes A Shares 0.0048 0.0363 0.0309 Returns After Taxes on Distributions A Shares 0.0102 0.0349 0.0305 Returns After Taxes on Distributions and Sale of Fund Shares A Shares 0.0186 0.0368 0.0317 Index Comparisons (Reflects no deduction for fees, expenses or taxes) Barclays 3-Year Municipal Bond Index 0.0296 0.0528 0.0426 Index Comparisons (Reflects no deduction for fees, expenses or taxes) Barclays 5-Year Municipal Bond Index ~ http://mfs.com/20130827/role/ScheduleAverageAnnualReturnsTransposed20022 column dei_LegalEntityAxis compact ck0000063075_S000002496Member column rr_PerformanceMeasureAxis compact * row primary compact * ~ <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">Aft</font><font size="2" style="font-size:10.0pt; font-family: Times New Roman;">er-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Your actual after-tax returns will depend on your own tax situation, and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k)&#160;plans or individual retirement accounts. The after-tax returns are shown for only one of the fund&#8217;s classes of shares, and after-tax returns for the fund&#8217;s other classes of shares will vary from the returns shown.</font> </p> mfs.com The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund's performance over time and how the fund's performance over time compares with that of a broad measure of market performance and one or more other measures of performance for markets in which the fund may invest. Average Annual Total Returns (for the Periods Ended December 31, 2012) Your actual after-tax returns will depend on your own tax situation, and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. The bar chart does not take into account any sales charges (loads) that you may be required to pay upon purchase or redemption of the fund's shares. If these sales charges were included, they would reduce the returns shown. The after-tax returns are shown for only one of the fund's classes of shares, and after-tax returns for the fund's other classes of shares will vary from the returns shown. 1-800-225-2606 (Reflects no deduction for fees, expenses or taxes) After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. The fund's past performance (before and after taxes) does not necessarily indicate how the fund will perform in the future. Fees and Expenses <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">This table describes the fees and expenses that you may pay when you buy and hold shares of the fund.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">You may qualify for sales charge reductions if you and certain members of your family invest, or agree to invest in the future, at least $50,000 in MFS Funds. More information about these and other waivers and reductions is available from your financial intermediary and in &#8220;Sales Charges and Waivers or Reductions&#8221; on page&#160;8 of the fund&#8217;s prospectus and &#8220;Waivers of Sales Charges&#8221; on page&#160;H-1 of the fund&#8217;s Statement of Additional Information (&#8220;SAI&#8221;).</font> </p> 0.0250 0.0000 0.0000 0.0000 0.0100 0.0400 0.0100 0.0000 0.0040 0.0040 0.0040 0.0040 0.0025 0.0100 0.0100 0.0000 0.0016 0.0016 0.0016 0.0016 0.0081 0.0156 0.0156 0.0056 -0.0011 -0.0011 -0.0001 -0.0001 0.0070 0.0145 0.0155 0.0055 ~ http://mfs.com/20130827/role/ScheduleShareholderFees20017 column dei_LegalEntityAxis compact ck0000063075_S000002496Member row primary compact * ~ ~ http://mfs.com/20130827/role/ScheduleAnnualFundOperatingExpenses20018 column dei_LegalEntityAxis compact ck0000063075_S000002496Member row primary compact * ~ You may qualify for sales charge reductions if you and certain members of your family invest, or agree to invest in the future, at least $50,000 in MFS Funds. Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): Shareholder Fees (fees paid directly from your investment): On shares purchased without an initial sales charge and redeemed within 18 months of purchase for shares purchased on or after August 1, 2012, and within 24 months of purchase for shares purchased prior to August 1, 2012. 2014-08-31 2014-08-31 50000 Portfolio Turnover <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The fund pays transaction costs, such as commissions, when it buys and sells securities (or &#8220;turns over&#8221; its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These transaction costs, which are not reflected in &#8220;Annual Fund Operating Expenses&#8221; or in the &#8220;Example,&#8221; affect the fund&#8217;s performance.&#160; During the most recent fiscal year, the fund&#8217;s portfolio turnover rate was 11% of the average value of its portfolio.</font> </p> 0.11 Principal Investment Strategies <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The fund invests, under normal market conditions, at least 80% of its net assets in securities and other investments, the interest on which is exempt from federal income tax. 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Updated performance is available online at <b>mfs.com</b> or by calling 1-800-225-2606.</font> </p> Class A Bar Chart. 0.0687 0.0472 0.0201 0.0414 0.0394 -0.0608 0.2071 0.0829 0.0647 0.0740 ~ http://mfs.com/20130827/role/ScheduleAnnualTotalReturnsBarChart20029 column dei_LegalEntityAxis compact ck0000063075_S000002497Member column rr_ProspectusShareClassAxis compact ck0000063075_C000006760Member row primary compact * ~ <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The bar chart does not take into account any sales charges (loads) that you may be required to pay upon purchase or redemption of the fund's shares. If these sales charges were included, they would reduce the returns shown.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-family: Times New Roman;"/> </p> highest quarterly return 0.0829 2009-06-30 lowest quarterly return -0.0324 2008-09-30 The total return for the six-month period ended -0.0238 2013-06-30 <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The total return for the six-month period ended June&#160;30, 2013 was (2.38)%. 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The after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. The bar chart does not take into account any sales charges (loads) that you may be required to pay upon purchase or redemption of the fund's shares. If these sales charges were included, they would reduce the returns shown. The after-tax returns are shown for only one of the fund's classes of shares, and after-tax returns for the fund's other classes of shares will vary from the returns shown. 1-800-225-2606 (Reflects no deduction for fees, expenses or taxes) After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. The fund's past performance (before and after taxes) does not necessarily indicate how the fund will perform in the future. Fees and Expenses <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">This table describes the fees and expenses that you may pay when you buy and hold shares of the fund. Expenses have been adjusted to reflect current fee arrangements.</font> </p> <br/><p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">You may qualify for sales charge reductions if you and certain members of your family invest, or agree to invest in the future, at least $50,000 in MFS Funds. 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Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): On shares purchased without an initial sales charge and redeemed within 18 months of purchase for shares purchased on or after August 1, 2012, and within 24 months of purchase for shares purchased prior to August 1, 2012. Shareholder Fees (fees paid directly from your investment): Expenses have been adjusted to reflect current fee arrangements. 2014-08-31 2014-08-31 2014-08-31 2014-08-31 2014-08-31 50000 Portfolio Turnover <p style="margin:0in 0in .0001pt;"> <font size="2" style="font-size:10.0pt; font-family: Times New Roman;">The fund pays transaction costs, such as commissions, when it buys and sells securities (or &#8220;turns over&#8221; its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. 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