<PAGE>
THIS FILING LISTS SECURITIES HOLDINGS REPORTED
ON THE FORM 13F FILED ON NOVEMBER 15, 1999
PURSUANT TO A REQUEST FOR
CONFIDENTIAL TREATMENT AND FOR WHICH
THAT REQUEST
EXPIRED ON MAY 15, 2000
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
Form 13F
FORM 13F COVER PAGE
Report for the Calendar Year or Quarter Ended: September 30, 1999
-------------------
Check here if Amendment [ X ]; Amendment Number: 2
--
This Amendment (Check only one.): [ ] is a restatement.
[X ] adds new holdings entries.
Institutional Investment Manager Filing this Report:
Name: Chesapeake Partners Management Co., Inc.
Address: 1829 Reisterstown Road
Suite 220
Baltimore, Maryland 21208
Form 13F File Number: 28- 4120
--------
The institutional investment manager filing this report and the person by whom
it is signed hereby represent that the person signing the report is authorized
to submit it, that all information contained herein is true, correct and
complete, and that it is understood that all required items, statements,
schedules, lists, and tables, are considered integral parts of this form.
Person Signing this Report on Behalf of Reporting Manager:
Name: Mark D. Lerner
Title: Vice President
Phone: (410) 602-0195
Signature, Place, and Date of Signing:
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<CAPTION>
<S> <C> <C>
/s/ Mark D. Lerner Baltimore, Maryland May 15, 2000
---------------------------------------- --------------------------------- ------------
[Signature] [City, State] [Date]
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Report Type (Check only one.):
[X] 13F HOLDINGS REPORT. (Check here if all holdings of this reporting manager
are reported in this report.)
[ ] 13F NOTICE. (Check here if no holdings reported are in this report, and
all holdings are reported by other reporting manager(s).)
[ ] 13F COMBINATION REPORT. (Check here if a portion of the holdings for
this reporting manager are reported in this report and a portion are
reported by other reporting manager(s).)
<PAGE>
FORM 13F SUMMARY PAGE
Report Summary:
Number of Other Included Managers: 0
------------
Form 13F Information Table Entry Total: 19
------------
Form 13F Information Table Value Total: $264,743
-------------
(thousands)
List of Other Included Managers:
Provide a numbered list of name(s) and Form 13F file number(s) of all
institutional investment managers with respect to which this report is filed,
other than the manager filing this report.
[If there are no entries in this list, state "NONE" and omit the column headings
and list entries.]
None
<PAGE>
FORM 13F INFORMATION TABLE
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<CAPTION>
COLUMN 1 COLUMN 2 COLUMN 3 COLUMN 4 COLUMN 5 COLUMN 6 COLUMN 7 COLUMN 8
-------- -------- -------- -------- -------- -------- -------- --------
TITLE OF VALUE SHRS OR SH/ PUT/ INVESTMENT OTHER VOTING AUTHORITY
NAME OF ISSUER CLASS CUSIP (x$1000) PRN AMT PRN CALL DISCRETION MANAGERS SOLE SHARED NONE
- ------------------------------------------------------------------------------------------------------------------------------------
<S> <C> <C> <C> <C> <C> <C> <C> <C> <C> <C> <C>
Aerial Comm. Common 007655103 1,259 46,400 SH SOLE SOLE
- ------------------------------------------------------------------------------------------------------------------------------------
AHT Corporation Common 00756H108 1,143 393,300 SH SOLE SOLE
- ------------------------------------------------------------------------------------------------------------------------------------
Alza Corporation Common 022615108 51,469 1,202,200 SH SOLE SOLE
- ------------------------------------------------------------------------------------------------------------------------------------
Atlantic Richfield Common 048825103 40,475 456,700 SH SOLE SOLE
- ------------------------------------------------------------------------------------------------------------------------------------
All, Inc. Common 05366B102 5,962 581,700 SH SOLE SOLE
- ------------------------------------------------------------------------------------------------------------------------------------
Eastern Utilities Common 277173100 1,201 40,200 SH SOLE SOLE
- ------------------------------------------------------------------------------------------------------------------------------------
First Security Corp Common 336294103 1,781 74,900 SH SOLE SOLE
- ------------------------------------------------------------------------------------------------------------------------------------
General Dynamics Common 369550108 8,360 133,900 SH SOLE SOLE
- ------------------------------------------------------------------------------------------------------------------------------------
General Instruments Common 370120107 26,827 558,900 SH SOLE SOLE
- ------------------------------------------------------------------------------------------------------------------------------------
Jones Intercable Common 480206200 6,163 114,000 SH SOLE SOLE
- ------------------------------------------------------------------------------------------------------------------------------------
Michael Foods Common 594079105 1,364 51,900 SH SOLE SOLE
- ------------------------------------------------------------------------------------------------------------------------------------
</TABLE>
<PAGE>
FORM 13F INFORMATION TABLE
<TABLE>
<CAPTION>
COLUMN 1 COLUMN 2 COLUMN 3 COLUMN 4 COLUMN 5 COLUMN 6 COLUMN 7 COLUMN 8
-------- -------- -------- -------- -------- -------- -------- --------
TITLE OF VALUE SHRS OR SH/ PUT/ INVESTMENT OTHER VOTING AUTHORITY
NAME OF ISSUER CLASS CUSIP (x$1000) PRN AMT PRN CALL DISCRETION MANAGERS SOLE SHARED NONE
- -----------------------------------------------------------------------------------------------------------------------------------
<S> <C> <C> <C> <C> <C> <C> <C> <C> <C> <C> <C>
New England Elec Common 644001109 3,190 61,500 SH SOLE SOLE
Omnipoint Corp. Common 68212D102 41,375 740,500 SH SOLE SOLE
Players International Common 727903106 548 74,000 SH SOLE SOLE
Reynolds Metals Common 761763101 43,875 726,700 SH SOLE SOLE
Sungard Data Systems Common 867363103 4,309 163,749 SH SOLE SOLE
Ventiv Health, Inc. Common 922793104 4,806 486,732 SH SOLE SOLE
Visio Corporation Common 927914101 6,374 162,400 SH SOLE SOLE
Waste Management Common 94106L109 14,262 740,900 SH SOLE SOLE
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