SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                                  SCHEDULE 13G
                                 (Rule 13d-102)

                 INFORMATION TO BE INCLUDED IN STATEMENTS FILED
                  PURSUANT TO RULES 13d-1(b), (c), AND (d) AND
               AMENDMENTS THERETO FILED PURSUANT TO RULE 13d-2(b)
                               (Amendment No. 1)*







                               UNISYS Corporation
--------------------------------------------------------------------------------
                                (Name of Issuer)



                          Common Stock, $0.01 par value
--------------------------------------------------------------------------------
                         (Title of Class of Securities)



                                    909214108
--------------------------------------------------------------------------------
                                 (CUSIP Number)



                                December 31, 2005
--------------------------------------------------------------------------------
             (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).


                                     Page 1



<PAGE>


CUSIP No.     909214108
              ----------------------

--------------------------------------------------------------------------------

     1)   Names of Reporting Person

          S.S. or I.R.S. Identification No. of Above Person

               Tudor Investment Corporation
          ----------------------------------------------------------------------
               22-2514825
          ----------------------------------------------------------------------

     2)   Check the Appropriate Box if a Member of a Group (See Instructions)

          (a)
              ------------------------------------------------------------------

          (b)    X
              ------------------------------------------------------------------

--------------------------------------------------------------------------------

     3)   SEC Use Only
                        --------------------------------------------------------

--------------------------------------------------------------------------------

     4)   Citizenship or Place of Organization    Delaware
                                                --------------------------------

--------------------------------------------------------------------------------
                    (5)  Sole Voting Power                               0
                                            ------------------------------------
Number of Shares    ------------------------------------------------------------
Beneficially        (6)  Shared Voting Power                    17,125,605
Owned by Each                                 ----------------------------------
Reporting Person    ------------------------------------------------------------
With                (7)  Sole Dispositive Power                          0
                                                  ------------------------------
                    ------------------------------------------------------------
                    (8)  Shared Dispositive Power               17,125,605
                                                   -----------------------------
--------------------------------------------------------------------------------

                     9)  Aggregate Amount Beneficially Owned
                         by Each Reporting Person               17,125,605
                                                             -------------------
--------------------------------------------------------------------------------

     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)         CO
                                                            --------------------
--------------------------------------------------------------------------------



                                     Page 2




<PAGE>


CUSIP No.     909214108
              ----------------------

--------------------------------------------------------------------------------

     1)   Names of Reporting Person

          S.S. or I.R.S. Identification No. of Above Person

               Paul Tudor Jones, II
          ----------------------------------------------------------------------
               
          ----------------------------------------------------------------------

     2)   Check the Appropriate Box if a Member of a Group (See Instructions)

          (a)
              ------------------------------------------------------------------

          (b)    X
              ------------------------------------------------------------------

--------------------------------------------------------------------------------

     3)   SEC Use Only
                        --------------------------------------------------------

--------------------------------------------------------------------------------

     4)   Citizenship or Place of Organization    USA
                                                --------------------------------

--------------------------------------------------------------------------------
                    (5)  Sole Voting Power                               0
                                            ------------------------------------
Number of Shares    ------------------------------------------------------------
Beneficially        (6)  Shared Voting Power                    18,667,300
Owned by Each                                 ----------------------------------
Reporting Person    ------------------------------------------------------------
With                (7)  Sole Dispositive Power                          0
                                                  ------------------------------
                    ------------------------------------------------------------
                    (8)  Shared Dispositive Power               18,667,300
                                                   -----------------------------
--------------------------------------------------------------------------------

                    9)   Aggregate Amount Beneficially Owned
                         by Each Reporting Person               18,667,300
                                                             -------------------
--------------------------------------------------------------------------------

     10)  Check if the Aggregate Amount in Row (9)
          Excludes Certain Shares (See Instructions)
                                                     ---------------------------
--------------------------------------------------------------------------------

     11)  Percent of Class Represented by Amount in Row 9            5.5%
                                                                ----------------
--------------------------------------------------------------------------------

     12)  Type of Reporting Person (See Instructions)         IN
                                                            --------------------
--------------------------------------------------------------------------------




                                     Page 3





<PAGE>



CUSIP No.     909214108
              ----------------------

--------------------------------------------------------------------------------

     1)   Names of Reporting Person

          S.S. or I.R.S. Identification No. of Above Person

               Tudor Proprietary Trading L.L.C.
          ----------------------------------------------------------------------
               13-3720063
          ----------------------------------------------------------------------

     2)   Check the Appropriate Box if a Member of a Group (See Instructions)

          (a)
              ------------------------------------------------------------------

          (b)    X
              ------------------------------------------------------------------

--------------------------------------------------------------------------------

     3)   SEC Use Only
                        --------------------------------------------------------

--------------------------------------------------------------------------------

     4)   Citizenship or Place of Organization    Delaware
                                                --------------------------------

--------------------------------------------------------------------------------
                    (5)  Sole Voting Power                               0
                                            ------------------------------------
Number of Shares    ------------------------------------------------------------
Beneficially        (6)  Shared Voting Power                     1,541,695
Owned by Each                                 ----------------------------------
Reporting Person    ------------------------------------------------------------
With                (7)  Sole Dispositive Power                          0
                                                  ------------------------------
                    ------------------------------------------------------------
                    (8)  Shared Dispositive Power                1,541,695
                                                   -----------------------------
--------------------------------------------------------------------------------

     9)   Aggregate Amount Beneficially Owned
          by Each Reporting Person                               1,541,695
                                                         -----------------------
--------------------------------------------------------------------------------

     10)  Check if the Aggregate Amount in Row (9)
          Excludes Certain Shares (See Instructions)
                                                     ---------------------------
--------------------------------------------------------------------------------

     11)  Percent of Class Represented by Amount in Row 9            0.5%
                                                                ----------------
--------------------------------------------------------------------------------

     12)  Type of Reporting Person (See Instructions)         OO
                                                            --------------------
--------------------------------------------------------------------------------




                                     Page 4




<PAGE>



CUSIP No.     909214108
              ----------------------

--------------------------------------------------------------------------------

     1)   Names of Reporting Person

          S.S. or I.R.S. Identification No. of Above Person

               The Tudor BVI Global Portfolio Ltd.
          ----------------------------------------------------------------------
               
          ----------------------------------------------------------------------

     2)   Check the Appropriate Box if a Member of a Group (See Instructions)

          (a)
              ------------------------------------------------------------------

          (b)    X
              ------------------------------------------------------------------

--------------------------------------------------------------------------------

     3)   SEC Use Only
                        --------------------------------------------------------

--------------------------------------------------------------------------------

     4)   Citizenship or Place of Organization    Cayman Islands
                                                --------------------------------

--------------------------------------------------------------------------------
                    (5)  Sole Voting Power                               0
                                            ------------------------------------
Number of Shares    ------------------------------------------------------------
Beneficially        (6)  Shared Voting Power                     2,881,839
Owned by Each                                 ----------------------------------
Reporting Person    ------------------------------------------------------------
With                (7)  Sole Dispositive Power                          0
                                                  ------------------------------
                    ------------------------------------------------------------
                    (8)  Shared Dispositive Power                2,881,839
                                                   -----------------------------
--------------------------------------------------------------------------------

     9)   Aggregate Amount Beneficially Owned
          by Each Reporting Person                               2,881,839
                                                         -----------------------
--------------------------------------------------------------------------------

     10)  Check if the Aggregate Amount in Row (9)
          Excludes Certain Shares (See Instructions)
                                                     ---------------------------
--------------------------------------------------------------------------------

     11)  Percent of Class Represented by Amount in Row 9            0.8%
                                                                ----------------
--------------------------------------------------------------------------------

     12)  Type of Reporting Person (See Instructions)         CO
                                                            --------------------
--------------------------------------------------------------------------------




                                     Page 5





<PAGE>



CUSIP No.     909214108
              ----------------------

--------------------------------------------------------------------------------

     1)   Names of Reporting Person

          S.S. or I.R.S. Identification No. of Above Person

               The Raptor Global Portfolio Ltd.
          ----------------------------------------------------------------------
               
          ----------------------------------------------------------------------

     2)   Check the Appropriate Box if a Member of a Group (See Instructions)

          (a)
              ------------------------------------------------------------------

          (b)    X
              ------------------------------------------------------------------

--------------------------------------------------------------------------------

     3)   SEC Use Only
                        --------------------------------------------------------

--------------------------------------------------------------------------------

     4)   Citizenship or Place of Organization    Cayman Islands
                                                --------------------------------

--------------------------------------------------------------------------------
                    (5)  Sole Voting Power                               0
                                            ------------------------------------
Number of Shares    ------------------------------------------------------------
Beneficially        (6)  Shared Voting Power                    14,111,042
Owned by Each                                 ----------------------------------
Reporting Person    ------------------------------------------------------------
With                (7)  Sole Dispositive Power                          0
                                                  ------------------------------
                    ------------------------------------------------------------
                    (8)  Shared Dispositive Power               14,111,042
                                                   -----------------------------
--------------------------------------------------------------------------------

     9)   Aggregate Amount Beneficially Owned
          by Each Reporting Person                              14,111,042
                                                         -----------------------
--------------------------------------------------------------------------------

     10)  Check if the Aggregate Amount in Row (9)
          Excludes Certain Shares (See Instructions)
                                                     ---------------------------
--------------------------------------------------------------------------------

     11)  Percent of Class Represented by Amount in Row 9            4.1%
                                                                ----------------
--------------------------------------------------------------------------------

     12)  Type of Reporting Person (See Instructions)         CO
                                                            --------------------
--------------------------------------------------------------------------------




                                     Page 6






<PAGE>



CUSIP No.     909214108
              ----------------------

--------------------------------------------------------------------------------

     1)   Names of Reporting Person

          S.S. or I.R.S. Identification No. of Above Person

               The Altar Rock Fund L.P.
          ----------------------------------------------------------------------
               06-1558414
          ----------------------------------------------------------------------

     2)   Check the Appropriate Box if a Member of a Group (See Instructions)

          (a)
              ------------------------------------------------------------------

          (b)    X
              ------------------------------------------------------------------

--------------------------------------------------------------------------------

     3)   SEC Use Only
                        --------------------------------------------------------

--------------------------------------------------------------------------------

     4)   Citizenship or Place of Organization    Delaware
                                                --------------------------------

--------------------------------------------------------------------------------
                    (5)  Sole Voting Power                               0
                                            ------------------------------------
Number of Shares    ------------------------------------------------------------
Beneficially        (6)  Shared Voting Power                       132,724
Owned by Each                                 ----------------------------------
Reporting Person    ------------------------------------------------------------
With                (7)  Sole Dispositive Power                          0
                                                  ------------------------------
                    ------------------------------------------------------------
                    (8)  Shared Dispositive Power                  132,724
                                                   -----------------------------
--------------------------------------------------------------------------------

     9)   Aggregate Amount Beneficially Owned
          by Each Reporting Person                                 132,724
                                                         -----------------------
--------------------------------------------------------------------------------

     10)  Check if the Aggregate Amount in Row (9)
          Excludes Certain Shares (See Instructions)
                                                     ---------------------------
--------------------------------------------------------------------------------

     11)  Percent of Class Represented by Amount in Row 9           0.04%
                                                                ----------------
--------------------------------------------------------------------------------

     12)  Type of Reporting Person (See Instructions)         PN
                                                            --------------------
--------------------------------------------------------------------------------




                                     Page 7




<PAGE>



 Item 1(a).    Name of Issuer:

               UNISYS Corporation

Item 1(b).     Address of Issuer's Principal Executive Offices:

               Unisys Way
               Blue Bell, PA  19424

Item 2(a).     Name of Person Filing:

               Tudor Investment Corporation ( "TIC")
               Paul Tudor Jones, II
               Tudor Proprietary Trading, L.L.C. ( "TPT")
               The Tudor BVI Global Portfolio Ltd. ( "BVI Portfolio")
               The Raptor Global Portfolio Ltd. ( "Raptor Portfolio")
               The Altar Rock Fund L.P. ( "Altar Rock")

Item 2(b).     Address of Principal Business Office or, if none, Residence:

               The principal business office of each of TIC, TPT, and Altar Rock
               is:

                           1275 King Street
                           Greenwich, CT 06831

               The principal business office of Mr. Jones is:

                           c/o Tudor Investment Corporation
                           1275 King Street
                           Greenwich, CT 06831

               The principal business office of each of Raptor Portfolio and BVI
               Portfolio is:

                           c/o CITCO
                           Kaya Flamboyan 9
                           P.O. Box 4774
                           Curacao, Netherlands Antilles

Item 2(c).     Citizenship:

               TIC is a Delaware corporation.
               Mr. Jones is a citizen of the United States.
               TPT is a Delaware limited liability company.
               Altar Rock is a Delaware limited partnership.
               Raptor Portfolio and BVI Portfolio are companies organized under
               the laws of the Cayman Islands.

Item 2(d).     Title of Class of Securities:

               Common Stock, par value $0.01

Item 2(e).     CUSIP Number:

               909214108



                                     Page 8




<PAGE>




Item 3.  If this statement is filed pursuant to Rules 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)(19) of the Act
         (d)   [  ] Investment Company registered under section 8 of the
                    Investment Company Act
         (e)   [  ] Investment Adviser registered under section 203 of the
                    Investment Advisers Act of 1940
         (f)   [  ] Employment Benefit Plan, Pension Fund which is subject to
                    the provisions of the Employee Retirement Income
                    Security Act of 1974 or Endowment Fund; 
                    see section 240.13d-1(b)(1)(ii)(F)
         (g)   [  ] Parent Holding Company, in accordance with
                    section 240.13d-1(b)(1)(ii)(G) (Note:  See Item 7)
         (h)   [  ] Group, in accordance with section 240.13d-1(b)(1)(ii)(H)

Item 4.  Ownership (As of December 31, 2005).


         (a)   Amount Beneficially Owned:  See Item 9 of cover pages

         (b)   Percent of Class:  See Item 11 of cover pages

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

               (i)    sole power to vote or to direct the vote
                                                       See Item 5 of cover pages
                                                       -------------------------
               (ii)   shared power to vote or to direct the vote
                                                       See Item 6 of cover pages
                                                       -------------------------
               (iii)  sole power to dispose or to direct the disposition of
                                                       See Item 7 of cover pages
                                                       -------------------------
               (iv)   shared power to dispose or to direct the disposition of
                                                       See Item 8 of cover pages
                                                       -------------------------

               The shares of Common Stock reported herein as beneficially owned
          are owned directly by TPT (1,541,695 shares), Raptor Portfolio
          (14,111,042 shares), BVI Portfolio (2,881,839 shares), and Altar Rock
          (132,724 shares). Because TIC provides investment advisory services to
          Raptor Portfolio and BVI Portfolio and is the general partner of Altar
          Rock, TIC may be deemed to beneficially own the shares of Common Stock
          owned by each of such Reporting Persons. TIC expressly disclaims such
          beneficial ownership. In addition, because Mr. Jones is the
          controlling shareholder of TIC and the indirect controlling equity
          holder of TPT, Mr. Jones may be deemed to beneficially own the shares
          of Common Stock deemed beneficially owned by TIC and TPT. Mr. Jones
          expressly disclaims such beneficial ownership.


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.

               See cover pages



                                     Page 9





<PAGE>


Item 9.  Notice of Dissolution of Group.

               Not applicable



                                    Page 10





<PAGE>


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.

              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.


                             Dated:       February 13, 2006


                             TUDOR INVESTMENT CORPORATION


                             By:          /s/ Stephen N. Waldman
                                  ----------------------------------------------
                                  Stephen N. Waldman
                                  Managing Director and
                                  Associate General Counsel




                                  /s/ Paul Tudor Jones, II
                             ---------------------------------------------------
                                  Paul Tudor Jones, II



                             TUDOR PROPRIETARY TRADING, L.L.C.


                             By:          /s/ Stephen N. Waldman
                                  ----------------------------------------------
                                  Stephen N. Waldman
                                  Managing Director and
                                  Associate General Counsel


                             THE TUDOR BVI GLOBAL PORTFOLIO LTD.

                             By:      Tudor Investment Corporation,
                                      Trading Advisor

                                    By:        /s/ Stephen N. Waldman
                                         ---------------------------------------
                                         Stephen N. Waldman
                                         Managing Director and
                                         Associate General Counsel



                                    Page 11





<PAGE>





                             THE RAPTOR GLOBAL PORTFOLIO LTD.

                             By:    Tudor Investment Corporation,
                                    Investment Advisor


                                    By:        /s/ Stephen N. Waldman
                                         ---------------------------------------
                                         Stephen N. Waldman
                                         Managing Director and
                                         Associate General Counsel

                             THE ALTAR ROCK FUND L.P.

                             By:    Tudor Investment Corporation,
                                    General Partner


                                    By:        /s/ Stephen N. Waldman
                                         ---------------------------------------
                                         Stephen N. Waldman
                                         Managing Director and
                                         Associate General Counsel




                                    Page 12