Massachusetts Investors Growth Stock Fund

Massachusetts Investors Growth Stock Fund Summary of Key Information

Investment Objective

The fund’s investment objective is to seek capital appreciation.

Fees and Expenses

This table describes the fees and expenses that you may pay when you buy and hold shares of the fund.

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 “Sales Charges and Waivers or Reductions” on page 7 of the fund’s Prospectus and “Waivers of Sales Charges” on page H-1 of the fund’s Statement of Additional Information (“SAI”).

Shareholder Fees (fees paid directly from your investment):

Shareholder Fees Massachusetts Investors Growth Stock Fund	A		529A	B	529B	C	529C	I	R1	R2	R3	R4	R5
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	5.75%		5.75%	none	none	none	none	none	none	none	none	none	none
Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, whichever is less)	1.00%	[1]	none	4.00%	4.00%	1.00%	1.00%	none	none	none	none	none	none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):

Annual Fund Operating Expenses Massachusetts Investors Growth Stock Fund		A	B	C	I	529A	529B	529C	R1	R2	R3	R4	R5
Management Fee		0.33%	0.33%	0.33%	0.33%	0.33%	0.33%	0.33%	0.33%	0.33%	0.33%	0.33%	0.33%
Distribution and/or Service (12b-1) Fees		0.25%	1.00%	1.00%	none	0.25%	1.00%	1.00%	1.00%	0.50%	0.25%	none	none
Other Expenses		0.16%	0.16%	0.16%	0.16%	0.26%	0.26%	0.26%	0.16%	0.16%	0.16%	0.16%	0.06%
Total Annual Fund Operating Expenses		0.74%	1.49%	1.49%	0.49%	0.84%	1.59%	1.59%	1.49%	0.99%	0.74%	0.49%	0.39%
Fee Reductions and/or Expense Reimbursements	[1]	none	none	none	none	(0.05%)	(0.05%)	(0.05%)	none	none	none	none	none
Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements		0.74%	1.49%	1.49%	0.49%	0.79%	1.54%	1.54%	1.49%	0.99%	0.74%	0.49%	0.39%

Example

This example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds.

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’s operating expenses remain the same.

Although your actual costs will likely be higher or lower, under these assumptions your costs would be:

Expense Example Massachusetts Investors Growth Stock Fund (USD $)	1 YEAR	3 YEARS	5 YEARS	10 YEARS
A	646	798	963	1,441
B	552	771	1,013	1,576
C	252	471	813	1,779
I	50	157	274	616
529A	651	823	1,010	1,548
529B	557	797	1,061	1,684
529C	257	497	861	1,885
R1	152	471	813	1,779
R2	101	315	547	1,213
R3	76	237	411	918
R4	50	157	274	616
R5	40	125	219	493

Expense Example No Redemption Massachusetts Investors Growth Stock Fund (USD $)	1 YEAR	3 YEARS	5 YEARS	10 YEARS
B	152	471	813	1,576
C	152	471	813	1,779
529B	157	497	861	1,684
529C	157	497	861	1,885

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” 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 “Annual Fund Operating Expenses” or in the “Example,” affect the fund’s performance.  During the most recent fiscal year, the fund’s portfolio turnover rate was 26% of the average value of its portfolio.

Principal Investment Strategies

MFS (Massachusetts Financial Services Company, the fund’s investment adviser) normally invests at least 80% of the fund’s net assets in stocks. Stocks include common stocks, preferred stocks, securities convertible into stocks, and depositary receipts for such securities.

MFS focuses on investing the fund’s assets in the stocks of companies it believes to have above average earnings growth potential compared to other companies (growth companies).

While MFS may invest the fund’s assets in companies of any size, MFS primarily invests in companies with large capitalizations.

MFS may invest the fund’s assets in foreign securities.

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 issuers. Quantitative models that systematically evaluate issuers may also be considered.

Principal Risks

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.

The principal risks of investing in the fund are:

Stock Market/Company Risk:  Stock markets are volatile and can decline significantly in response to issuer, market, economic, industry, political, regulatory, geopolitical, and other conditions, as well as to investor perceptions of these conditions. The price of an equity security can decrease significantly in response to these conditions, and these conditions can affect a single issuer or type of security, issuers within a broad market sector, industry or geographic region, or the market in general.

Growth Company Risk:  The stocks of growth companies can be more sensitive to the company’s earnings and more volatile than the market in general.

Foreign Risk:  Exposure to foreign markets through issuers or currencies 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.

Liquidity Risk:  It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may have to sell certain of these investments at a price or time that is not advantageous in order to meet redemptions or other cash needs.

Investment Selection Risk:  MFS’ 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.

Performance Information

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.

The fund’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 mfs.com or by calling 1-800-225-2606.

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.

Class A Bar Chart.

During the period(s) shown in the bar chart, the highest quarterly return was 16.83% (for the calendar quarter ended June 30, 2009) and the lowest quarterly return was (23.72)% (for the calendar quarter ended December 31, 2008).

Performance Table.

Average Annual Total Returns (For the Periods Ended December 31, 2014)

Average Annual Returns Massachusetts Investors Growth Stock Fund	Label	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
B	Returns Before Taxes B Shares	6.64%	13.36%	7.45%
C	Returns Before Taxes C Shares	9.59%	13.60%	7.29%
I	Returns Before Taxes I Shares	11.78%	14.75%	8.36%
529A	Returns Before Taxes 529A Shares	5.01%	13.04%	7.26%
529B	Returns Before Taxes 529B Shares	6.59%	13.31%	7.31%
529C	Returns Before Taxes 529C Shares	9.63%	13.53%	7.15%
R1	Returns Before Taxes R1 Shares	10.68%	13.61%	7.23%
R2	Returns Before Taxes R2 Shares	11.22%	14.17%	7.77%
R3	Returns Before Taxes R3 Shares	11.49%	14.46%	8.03%
R4	Returns Before Taxes R4 Shares	11.77%	14.75%	8.33%
R5	Returns Before Taxes R5 Shares	11.89%	14.81%	8.39%
A	Returns Before Taxes A Shares	5.11%	13.10%	7.39%
After Taxes on Distributions A	Returns After Taxes on Distributions A Shares	4.20%	12.75%	7.20%
After Taxes on Distributions and Sale of Fund Shares A	Returns After Taxes on Distributions and Sale of Fund Shares A Shares	3.65%	10.50%	6.00%
Russell 1000 Growth Index	Index Comparison (Reflects no deduction for fees, expenses, or taxes) Russell 1000 Growth Index	13.05%	15.81%	8.49%

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. 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 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] This contingent deferred sales charge (CDSC) applies to shares purchased without an initial sales charge and redeemed within 18 months of purchase.

[1] 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 March 31, 2016, unless MFS Fund Distributors, Inc., elects to extend the waiver.