<SEC-DOCUMENT>0001419078-12-000008.txt : 20120207
<SEC-HEADER>0001419078-12-000008.hdr.sgml : 20120207
<ACCEPTANCE-DATETIME>20120207130409
ACCESSION NUMBER:		0001419078-12-000008
CONFORMED SUBMISSION TYPE:	SC 13G
PUBLIC DOCUMENT COUNT:		1
FILED AS OF DATE:		20120207
DATE AS OF CHANGE:		20120207

SUBJECT COMPANY:	

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ARCH CAPITAL GROUP LTD.
		CENTRAL INDEX KEY:			0000947484
		STANDARD INDUSTRIAL CLASSIFICATION:	FIRE, MARINE & CASUALTY INSURANCE [6331]
		IRS NUMBER:				000000000
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		SC 13G
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	005-45257
		FILM NUMBER:		12576733

	BUSINESS ADDRESS:	
		STREET 1:		WESSEX HOUSE
		STREET 2:		45 REID STREET
		CITY:			HAMILTON
		STATE:			D0
		ZIP:			HM 12
		BUSINESS PHONE:		441-278-9250

	MAIL ADDRESS:	
		STREET 1:		WESSEX HOUSE
		STREET 2:		45 REID STREET
		CITY:			HAMILTON
		STATE:			D0
		ZIP:			HM 12

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ARCH CAPITAL GROUP LTD
		DATE OF NAME CHANGE:	20000508

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	RISK CAPITAL HOLDINGS INC
		DATE OF NAME CHANGE:	19950816

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	RISK CAPITAL RE INC
		DATE OF NAME CHANGE:	19950703

FILED BY:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			BART PARTNERS, LLC
		CENTRAL INDEX KEY:			0001419078
		IRS NUMBER:				261073073
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		SC 13G

	BUSINESS ADDRESS:	
		STREET 1:		199 FREMONT STREET
		STREET 2:		SUITE 2500
		CITY:			SAN FRANCISCO
		STATE:			CA
		ZIP:			94105-2261
		BUSINESS PHONE:		415-284-8888

	MAIL ADDRESS:	
		STREET 1:		199 FREMONT STREET
		STREET 2:		SUITE 2500
		CITY:			SAN FRANCISCO
		STATE:			CA
		ZIP:			94105-2261

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	BART Partners, LLC
		DATE OF NAME CHANGE:	20071120
</SEC-HEADER>
<DOCUMENT>
<TYPE>SC 13G
<SEQUENCE>1
<FILENAME>bart13gacgl020712.txt
<TEXT>
                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                              Washington, DC 20549

                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934
                               (Amendment No. 0)*


                             Arch Capital Group Ltd.
-------------------------------------------------------------------------------
                                (Name of Issuer)


                                  Common Shares
-------------------------------------------------------------------------------
                         (Title of Class of Securities)


                                    G0450A105
-------------------------------------------------------------------------------
                                 (CUSIP Number)


                                February 6, 2012
-------------------------------------------------------------------------------
             (Date of Event which Requires Filing of this Statement)


Check the appropriate box to designate the rule pursuant to which this Schedule
                                   is filed:

|_|      Rule 13d-1(b)
|X|      Rule 13d-1(c)
|_|      Rule 13d-1(d)

* The remainder of this cover page shall be filled out for a reporting  person's
initial filing on this form with respect to the subject class of securities, and
for any  subsequent  amendment  containing  information  which  would  alter the
disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the  Securities  Exchange  Act of
1934 ("Act") or otherwise  subject to the liabilities of that section of the Act
but  shall be  subject  to all other  provisions  of the Act  (however,  see the
Notes).

                         (Continued on following pages)
                               Page 1 of 4 Pages


<PAGE>


                                       13G
===================
CUSIP No. G0450A105
===================

================================================================================
    1       NAMES OF REPORTING PERSONS
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

            BART Partners, LLC
================================================================================
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions)
                                                              (a) [   ]
                                                              (b) [   ]


================================================================================
    3       SEC USE ONLY


================================================================================
    4       CITIZENSHIP OR PLACE OF ORGANIZATION

            Delaware
================================================================================
                           5       SOLE VOTING POWER

                                   6,709,755
         NUMBER OF     =========================================================
          SHARES           6       SHARED VOTING POWER
       BENEFICIALLY
         OWNED BY                  0
           EACH        =========================================================
         REPORTING         7       SOLE DISPOSITIVE POWER
        PERSON WITH
                                   6,709,755
                       =========================================================
                           8       SHARED DISPOSITIVE POWER

                                   0
================================================================================
    9       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            6,709,755
================================================================================
    10      CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES
            CERTAIN SHARES (See Instructions)                     [   ]

================================================================================
    11      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

            5.0%
================================================================================
    12      TYPE OF REPORTING PERSON (See Instructions)

            IA
================================================================================


                               Page 2 of 4 Pages
<PAGE>


Item 1.  Issuer
         ------

        (a) Name of Issuer:
            --------------

            Arch Capital Group Ltd.

        (b) Address of Issuer's Principal Executive Offices:
            -----------------------------------------------

            Wessex House
	    45 Reid Street
	    Hamilton HM 12
	    Bermuda


Item 2.	 Identity And Background
         -----------------------

	(a) Name of Person Filing:
            ---------------------

            BART Partners, LLC

        (b) Address of Principal Business Office or, if none, Residence:
            -----------------------------------------------------------

	    199 Fremont Street
            Suite 2500
            San Francisco, CA 94105-2261

	(c) Citizenship:
            -----------

            Delaware

	(d) Title of Class of Securities:
            ----------------------------

	    Common Shares

	(d) CUSIP Number:
            ------------

	    G0450A105


Item 3.  If this statement is filed pursuant to 240.13d-1(b) or
	 240.13d-2(b) or (c), check whether the person filing is a:
         ---------------------------------------------------------

	(a) [ ] Broker or dealer registered under section 15 of the
		Act (15 U.S.C. 78o);

	(b) [ ] Bank as defined in section 3(a)(6) of the Act
	        (15 U.S.C. 78c);

	(c) [ ] Insurance company as defined in section 3(a)(19) of
		the Act (15 U.S.C. 78c);

	(d) [ ] Investment company registered under section 8 of the
		Investment Company Act of 1940 (15 U.S.C 80a-8);

	(e) [ ] An investment adviser in accordance with
		240.13d-1(b)(1)(ii)(E);

	(f) [ ] An employee benefit plan or endowment fund in accordance
		with 240.13d-1(b)(1)(ii)(F);

	(g) [ ] A parent holding company or control person in accordance
		with 240.13d-1(b)(1)(ii)(G);

	(h) [ ] A savings associations as defined in Section 3(b) of
		the Federal Deposit Insurance Act (12 U.S.C. 1813);

	(i) [ ] A church plan that is excluded from the definition
		of an investment company under section 3(c)(14) of
		the Investment Company Act of 1940 (15 U.S.C. 80a-3);

	(j) [ ] A non-U.S. institution in accordance with
		240.13d-1(b)(1)(ii)(J);

	(k) [ ] Group, in accordance with 240.13d-1(b)(1)(ii)(K).

	    [X] If this statement is filed in pursuant to a 240.13d-1(c),
		check this box


Item 4.  Ownership
         ---------

	(a) Amount beneficially owned: 6,709,755

	(b) Percent of class: 5.0%

	(c) Number of shares as to which the person has:

		(i) Sole power to vote or to direct the vote: 6,709,755

		(ii) Shared power to vote or to direct the vote: 0

		(iii) Sole power to dispose or to direct the disposition of: 6,709,755

		(iv) Shared power to dispose or to direct the disposition of: 0


Item 5.  Ownership Of Five Percent Or Less Of a Class
         --------------------------------------------

         Not Applicable.


Item 6.  Ownership Of More Than Five Percent On Behalf Of Another Person
         ---------------------------------------------------------------

         Not Applicable.


Item 7.  Identification  And Classification Of The Subsidiary Which Acquired The
         -----------------------------------------------------------------------
         Security Being Reported On By The Parent Holding Company
         --------------------------------------------------------

         Not Applicable.


Item 8.  Identification And Classification Of Members Of The Group
         ---------------------------------------------------------

         Not Applicable.


Item 9.  Notice Of Dissolution Of Group
         ------------------------------

         Not Applicable.


Item 10. Certification
         -------------

         By  signing  below I  certify  that,  to the best of my  knowledge  and
belief, the securities  referred to above were not acquired and are not held for
the purpose of or with the effect of changing or influencing  the control of the
issuer of the  securities  and were not acquired and are not held in  connection
with or as a participant in any transaction having that purpose or effect.


                              Page 3 of 4 Pages
<PAGE>


                                   SIGNATURES
                                   ----------

         After  reasonable  inquiry and to the best of our knowledge and belief,
the  undersigned  certify that the  information  set forth in this  statement is
true, complete and correct.


Dated:  February 7, 2012

               /s/ Stephen D. Lane
               ----------------------------------------
               Chief Financial Officer
	       BART Partners, LLC


                              Page 4 of 4 Pages


</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>