<PAGE>
THIS FILING LISTS SECURITIES HOLDINGS REPORTED
ON THE FORM 13F FILED ON NOVEMBER 13, 1998,
PURSUANT TO A REQUEST FOR
CONFIDENTIAL TREATMENT AND FOR WHICH
THAT REQUEST WAS DENIED OR CONFIDENTIAL TREATMENT
EXPIRED ON SEPTEMBER 30, 1999
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, 1998
Check here if Amendment [x]; Amendment Number: 3
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:
/s/ Mark D. Lerner Baltimore, Maryland 10/07/99
[Signature] [City, State] [Date]
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: 1
Form 13F Information Table Value Total: $6,376
(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
<TABLE>
<CAPTION>
COLUMN 1 COLUMN 2 COLUMN 3 COLUMN 4 COLUMN 5 COLUMN 6 COLUMN 7 COLUMN 8
- --------------------- -------- --------- -------- ------------------ ---------- -------- ------------------
TITLE VALUE SHRS OR SH/ PUT/ INVESTMENT OTHER VOTING AUTHORITY
NAME OF ISSUER OF 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>
IPC Information Sys Common 44980k206 6,376 927,400 SH SOLE SOLE
</TABLE>
