UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13G/A

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

                       Platinum Underwriters Holdings, Ltd.
- --------------------------------------------------------------------------------
                                (Name of Issuer)

                     Common Stock, Par Value $.001 Per Share
- --------------------------------------------------------------------------------
                         (Title of Class of Securities)

                                   G7127P100
- --------------------------------------------------------------------------------
                                 (CUSIP Number)

                                December 31, 2010
- --------------------------------------------------------------------------------
             (Date of Event Which Requires Filing of this Statement)

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

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


CUSIP NO.  G7127P100


- --------------------------------------------------------------------------------
1     NAME OF REPORTING PERSON
      SS OR IRS IDENTIFICATION NO. OF ABOVE PERSON

      Aronson+Johnson+Ortiz, LP
      23-2312104
- --------------------------------------------------------------------------------
2     CHECK APPROPRIATE BOX IF A MEMBER OF A GROUP                       (a) |_|
                                                                         (b) |_|
- --------------------------------------------------------------------------------
3     SEC USE ONLY

- --------------------------------------------------------------------------------
4     CITIZENSHIP OR PLACE OF ORGANIZATION

      Delaware
- --------------------------------------------------------------------------------
                  5     SOLE VOTING POWER

                        256,400
 NUMBER OF        --------------------------------------------------------------
  SHARES          6     SHARED VOTING POWER
BENFICIALLY
 OWNED BY               0
   EACH           --------------------------------------------------------------
 REPORTING        7     SOLE DISPOSITIVE POWER
  PERSON
   WITH                 265,300
                  --------------------------------------------------------------
                  8     SHARED DISPOSITIVE POWER

                        0
- --------------------------------------------------------------------------------
9     AGGREGATE AMOUNT BENFICIALLY OWNED BY EACH REPORTING PERSON

      265,300
- -------------------------------------------------------------------------------
10    CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES CERTAIN SHARES   |_|

- --------------------------------------------------------------------------------
11    PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

      .7%
- --------------------------------------------------------------------------------
12    TYPE OF REPORTING PERSON

      IA
- --------------------------------------------------------------------------------




Item  1.

            a) Name of Issuer:      Platinum Underwritings Holdings, Ltd.
            b) Address:             The Belvedere Building, 69 Pitts Bay Road
				    Pembroke, HM 08 Bermuda
Item  2.
            a) Name of Filer:       Aronson+Johnson+Ortiz, LP


            b) Address of Filer:    230 S. Broad Street, 20th Floor
                                    Philadelphia, PA 19102

            c) Citizenship:         Delaware

            d) Title of Class of Securities: Common Stock, Par Value $.001

            e) CUSIP Number: 	    G7127P100

Item 3. Item 3. If this statement is filed pursuant to Rule 13d-1(b), or
13d-2(b), check whether the person filing is a:

      (a)   |_|   Broker or Dealer registered under Section 15 of the Act
      (b)   |_|   Bank as defined in section 3 (a) (6) of the Act
      (c)   |_|   Insurance Company as defined in section 3 (a) (6) of the Act
      (d)   |_|   Investment Company registered under section 8 of the
                  Investment Company Act
      (e)   |X|   Investment Adviser registered under section 203 of the
                  Investment Advisers act of 1940
      (f)   |_|   Employee Benefit Plan, Pension Fund which is subject to the
                  provisions of the Employee Retirement Income Security Act of
                  1974 or Endowment Fund; see 240.13d-1 (b) (1) (ii) (F)
      (g)   |_|   Parent Holding Company, in accordance with 240.13d-1 (b) (ii)
                  (G) (Note: See Item 7)
      (h)   |_|   Group, in accordance with 240.13d-1(b) (1) (ii) (H)

Item 4.  Ownership

            a)    Amount beneficially owned: 265,300
            b)    Percent of Class: .7%
            c)    Number of shares:

                  (i)   Sole voting power -- 256,400
                  (ii)  Shared voting power -- 0
                  (iii) Sole disposal power -- 265,300
                  (iv)  Shared disposal power - 0


Item 5.    Less than 5% beneficial ownership
           If this statement is being filed to report the fact that as
           of the date hereof the reporting person has ceased to be the
           beneficial owner of more than five percent of the class of
           securities, check the following [x ].

Item 6.    More than 5% on behalf of another person

The securities as to which this schedule is filed by
Aronson+Johnson+Ortiz, LP, in its capacity as investment
adviser, are owned of record by clients of Aronson+Johnson+Ortiz,LP.
No such client is known to own more than five percent of this
class of securities.

Item 7.    Subsidiary     na

Item 8.    If group     na

Item 9.    Notice of Dissolution      na

Item 10.   Certification

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

                                    SIGNATURE

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

February 15, 2011
      Date

Aronson+Johnson+Ortiz, LP


By: /s/ Joseph F. Dietrick, Chief Compliance Officer
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            Name, Title