UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, DC 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
(AMENDMENT NO. 3)*
Mercury Computer Systems Inc
__________________________________________________________________
(Name of Issuer)
Common
__________________________________________________________________
(Title of Class of Securities)
589378108
__________________________________________________________________
(CUSIP Number)
December 31, 1999
__________________________________________________________________
(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).
Page 1 of 6 Pages
<PAGE>
CUSIP No. 589378108 13G
__________________________________________________________________
1. NAME OF REPORTING PERSON
S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON
Massachusetts Mutual Life Insurance Company
04-1590850
__________________________________________________________________
2. CHECK THE APPROPRIATE BOX IF MEMBER OF A GROUP
(A) _______
(B) __x____
__________________________________________________________________
3. SEC USE ONLY
__________________________________________________________________
4. CITIZENSHIP OF PLACE OF ORGANIZATION
Commonwealth of Massachusetts
__________________________________________________________________
5. SOLE VOTING POWER
NUMBER OF
SHARES 53,044
________________________________________________
BENEFICIALLY 6. SHARED VOTING POWER
OWNED BY
EACH not applicable
________________________________________________
REPORTING 7. SOLE DISPOSITIVE POWER
PERSON
WITH 53,044
_______________________________________________
8. SHARED DISPOSITIVE POWER
not applicable
__________________________________________________________________
9. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING
PERSON
53,044
__________________________________________________________________
10. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES
CERTAIN SHARES *
Not applicable
__________________________________________________________________
11. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
0.2%
__________________________________________________________________
12. TYPE OF REPORTING PERSON (See instructions)
IC (insurance company)
__________________________________________________________________
Page 2 of 6 Pages
<PAGE>
CUSIP No. 589378108 13G
__________________________________________________________________
1. NAME OF REPORTING PERSON
S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON
MassMutual Corporate Investors
04-2483041
__________________________________________________________________
2. CHECK THE APPROPRIATE BOX IF MEMBER OF A GROUP
(A) _______
(B) __x____
__________________________________________________________________
3. SEC USE ONLY
__________________________________________________________________
4. CITIZENSHIP OF PLACE OF ORGANIZATION
Commonwealth of Massachusetts
__________________________________________________________________
5. SOLE VOTING POWER
NUMBER OF
SHARES 72,088
________________________________________________
BENEFICIALLY 6. SHARED VOTING POWER
OWNED BY
EACH not applicable
________________________________________________
REPORTING 7. SOLE DISPOSITIVE POWER
PERSON
WITH 72,088
________________________________________________
8. SHARED DISPOSITIVE POWER
not applicable
__________________________________________________________________
9. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING
PERSON
72,088
__________________________________________________________________
10. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES
CERTAIN SHARES *
not applicable
__________________________________________________________________
11. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
0.3%
__________________________________________________________________
12. TYPE OF REPORTING PERSON *
IV (investment company)
__________________________________________________________________
Page 3 of 6 Pages
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ITEM 1(a). Name of Issuer: Mercury Computer Systems Inc
ITEM 1(b). Address of Issuer's Principal Executive Offices:
199 Riverneck Road
Chelmsford, MA 01824-2820
ITEM 2(a). Name of Person Filing:
This statement is filed on behalf of Massachusetts
Mutual Life Insurance Company and MassMutual
Corporate Investors, which together may be
regarded as a group for the purpose of this
statement. This statement is signed on behalf
of both the aforementioned parties, and therefore
it does not include a separate agreement
providing for a joint filing.
ITEM 2(b). Address of Principal Business Office:
MASSACHUSETTS MUTUAL LIFE INSURANCE COMPANY
1295 State Street
Springfield, Massachusetts 01111
MASSMUTUAL CORPORATE INVESTORS
1295 State Street
Springfield, Massachusetts 01111
ITEM 2(c). Citizenship
MASSACHUSETTS MUTUAL LIFE INSURANCE COMPANY is
organized under the laws of the Commonwealth of
Massachusetts
MASSMUTUAL CORPORATE INVESTORS is
organized under the laws of the Commonwealth of
Massachusetts
ITEM 2(d). Title of Class of Securities: Common Stock
ITEM 2(e). CUSIP NUMBER: 589378108
ITEM 3. This statement is filed pursuant to Rule 13d-1(b) by
Massachusetts Mutual Life Insurance Company,
an insurance company as defined in Section 3(a)(19),
MassMutual Corporate Investors, an investment
company registered under Section 8 of the Investment
Company Act of 1940 which together may be
regarded as a group pursuant to Rule
13d-1(b) (ii) (H).
ITEM 4. Ownership:
This statement if filed to report information as of
December 31,1999:
Page 4 of 6 Pages
<PAGE>
(a) Amount Beneficially Owned:
Massachusetts Mutual Life Insurance Company and
MassMutual Corporate Investors own respectively
53,044 and 72,088 shares of common stock.
Total shares of common stock owned directly and
indirectly: 125,132
The filing of this statement shall not be construed
as an admission that Massachusetts Mutual Life
Insurance Company and MassMutual Corporate Investors
are for the purposes of sections 13(d) and 13(g)
of the Securities Exchange Act of 1934, the
beneficial owners of any common stock of the issuer.
(b) Percent of Class:
Percentage of ownership is calculated as follows:
125,132(shares held) / 20,840,000 (shares outstanding)
= 0.6%
(c) Powers:
Massachusetts Mutual Life Insurance Company and
MassMutual Corporate Investors each have sole power
to vote or dispose of respectively 53,044
and 72,088 shares of common stock.
ITEM 5. Ownership of Five Percent or Less of a Class:
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. 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 the Group:
Not applicable
Page 5 of 6 Pages
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ITEM 10. Certification:
By signing below, MASSACHUSETTS MUTUAL LIFE
INSURANCE COMPANY, MASSMUTUAL CORPORATE
INVESTORS certify to the best of their
knowledge and belief, the securities referred to
above were acquired and are held in the ordinary
course of business and 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 such
securities and were not acquired in connection
with or as a participant in any transaction having
such purpose or effect.
After reasonable inquiry and to the best of our
knowledge and belief, MASSACHUSETTS MUTUTAL LIFE
INSURANCE COMPANY and MASSMUTUAL CORPORATE INVESTORS
certify that the information set forth in this
statement is true, complete and correct.
February 3, 2000 February 3, 2000
(Date) (Date)
MASSACHUSETTS MUTUAL MASSMUTUAL CORPORATE
LIFE INSURANCE COMPANY INVESTORS
By: /signature/ By: /signature/
Charles McCobb Charles McCobb
Managing Director Managing Director
Page 6 of 6 Pages
