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                     U.S. SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                     FORM 4

                  STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

    Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934,
       Section 17(a) of the Public Utility Holding Company Act of 1935 or
               Section 30(f) of the Investment Company Act of 1940

[  ] Check this box if no longer subject of Section 16. Form 4 or Form 5
     obligations may continue. See Instruction 1(b).

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1. Name and Address of Reporting Person

      Mancuso, Vincent A.
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   (Last)               (First)                 (Middle)

      9213 Vendome Drive
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                                    (Street)

      Bethesda, Maryland  20817
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   (City)               (State)                 (Zip)


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2. Issuer Name and Ticker or Trading Symbol


      Mercury Computer Systems, Inc. ("MRCY")
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3. IRS or Social Security Number of Reporting Person (Voluntary)


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4. Statement for Month/Year

      December 2000
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5. If Amendment, Date of Original (Month/Year)

      December 2000
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6. Relationship of Reporting Person to Issuer
   (Check all applicable)

   [   ]   Director                             [   ]   10% Owner
   [ X ]   Officer (give title below)           [   ]   Other (specify below)


      Vice President and Director of Government Electronics Group
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7.  Individual or Joint/Group Filing (Check Applicable Line)
   [X  ]   Form filed by One Reporting Person

   [   ]   Form filed by More than One Reporting Person
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           Table I -- Non-Derivative Securities Acquired, Disposed of,
                             or Beneficially Owned
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6. 4. 5. Owner- Securities Acquired (A) or Amount of ship 3. Disposed of (D) Securities Form: 7. Transaction (Instr. 3, 4 and 5) Beneficially Direct Nature of 2. Code ------------------------------- Owned at End (D) or Indirect 1. Transaction (Instr. 8) (A) of Month Indirect Beneficial Title of Security Date ------------ Amount or Price (Instr. 3 (I) Ownership (Instr. 3) (mm/dd/yy) Code V (D) and 4) (Instr.4) (Instr. 4) - ------------------------------------------------------------------------------------------------------------------------------------ Common Stock 12/07/00 S 1,000 D 36.375 - ----------------------------------------------------------------------------------------------------------------------------------- Common Stock 12/11/00 S 1,500 D 40.875 23,170(1) D - ------------------------------------------------------------------------------------------------------------------------------- Common Stock 12/09/99 M 800 A 7.625 - ----------------------------------------------------------------------------------------------------------------------------------- Common Stock 12/09/99 M 10,000 A 2.00 - ----------------------------------------------------------------------------------------------------------------------------------- Common Stock 02/17/00 M 5,000 A 2.00 - ----------------------------------------------------------------------------------------------------------------------------------- Common Stock 06/22/00 M 5,000 A 2.00 - ----------------------------------------------------------------------------------------------------------------------------------- ==================================================================================================================================== (1) Includes 2,666 shares acquired under the Mercury Computer Systems, Inc. Employee Stock Purchase Plan (the "Purchase Plan") in December 1998; 944 shares acquired under the Purchase Plan in June 1999; 483 shares acquired under the Purchase Plan in December 1999; 376 shares acquired under the Purchase Plan in June 2000 and 401 shares acquired under the Purchase Plan in December 2000.
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly FORM 4 (continued) Table II -- Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities) ================================================================================
9. 10. Number Owner- of ship 2. Deriv- of Conver- 5. 7. ative Deriv- 11. sion Number of Title and Amount Secur- ative Nature of Derivative 6. of Underlying 8. ities Secur- of Exer- 4. Securities Date Securities Price Bene- ity: In- cise 3. Trans- Acquired (A) Exercisable and (Instr. 3 and 4) of ficially Direct direct Price Trans- action or Disposed Expiration Date ---------------- Deriv- Owned (D) or Bene- 1. of action Code of(D) (Month/Day/Year) Amount ative at End In- ficial Title of Deriv- Date (Instr. (Instr. 3, ---------------- or Secur- of direct Owner- Derivative ative (Month/ 8) 4 and 5) Date Expira- Number ity Month (I) ship Security Secur- Day/ ------ ------------ Exer- tion of (Instr. (Instr. (Instr. (Instr. (Instr. 3) ity Year) Code V (A) (D) cisable Date Title Shares 5) 4) 4) 4) - ------------------------------------------------------------------------------------------------------------------------------------ - -------------------------------------------------------------------------------------------------------------------------------- Stock Option (Right to Buy) $7.625 09/28/98 A 4,000 (2) 09/28/08 Common 4,000 D - ----------------------------------------------------------------------------------------------------------------------------------- Stock Option (Right to Buy) $7.625 12/09/99 M 800 (2) 09/28/08 Common 800 3,200 D - ----------------------------------------------------------------------------------------------------------------------------------- Stock Option (Right to Buy) $23.438 11/02/99 A 13,462 (3) 11/02/09 Common 13,462 13,462 D - ----------------------------------------------------------------------------------------------------------------------------------- Stock Option (Right to Buy) $23.438 11/02/99 A 4,538 (4) 11/02/09 Common 4,538 4,538 D - ----------------------------------------------------------------------------------------------------------------------------------- Stock Option (Right to Buy) $30.063 10/10/00 A 1,750 (5) 10/10/10 Common 1,750 1,750 D - ----------------------------------------------------------------------------------------------------------------------------------- Stock Option (Right to Buy) $30.063 10/10/00 A 5,250 (6) 10/10/10 Common 5,250 5,250 D - ----------------------------------------------------------------------------------------------------------------------------------- Stock Option (Right to Buy) $2.00 12/09/99 M 10,000 (7) 01/27/07 Common 10,000 D - ----------------------------------------------------------------------------------------------------------------------------------- Stock Option (Right to Buy) $2.00 02/17/00 M 5,000 (7) 01/27/07 Common 5,000 D - ----------------------------------------------------------------------------------------------------------------------------------- Stock Option (Right to Buy) $2.00 06/22/00 M 5,000 (7) 01/27/07 Common 5,000 30,000 D ==================================================================================================================================== Explanation of Responses: (2) This option is exercisable as to 800 shares on each of September 28, 1999, September 28, 2000, September 28, 2001, September 28, 2002 and September 28, 2003. (3) This option is exercisable as to 3,152 shares on each of November 2, 2000, November 2, 2001 and November 2, 2002, and is exercisable as to 4,006 shares on November 2, 2003. (4) This option is exercisable as to 1,348 shares on each of November 2, 2000, November 2, 2001 and November 2, 2002, and is exercisable as to 494 shares on November 2, 2003. (5) This option is exercisable as to 1,750 shares on October 10, 2004. (6) This option is exercisable as to 1,750 shares on each of October 10, 2001, October 10, 2002 and October 10, 2003. (7) This option is exercisable as to 10,000 shares on each of January 27, 1998, January 27, 1999, January 27, 2000, January 27, 2001 and January 27, 2002.
/s/Vincent A. Mancuso March , 2001 - --------------------------------------------- ----------------------- **Signature of Reporting Person Date ** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a). Note: File three copies of this Form, one of which must be manually signed. If space provided is insufficient, see Instruction 6 for procedures. Potential persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.