UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    Form 13F
                               Form 13F COVER PAGE
Report for the Calendar Year or Quarter Ended: 3/31/2013
Check here if Amendment []; Amendment Number:
                                               -------
This Amendment (Check only one.):               [] is a restatement.
                                                [] adds new holdings entries.

Institutional Investment Manager Filing this Report:


Name:      Chesapeake Partners Management Co., Inc.

Address:   2800 Quarry Lake Drive
           Suite 300
           Baltimore, Maryland 21209


Form 13F File Number: 28-04120


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 submission.

Persons 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                5/15/2013
---------------------------------  ---------------------------------  ----------
[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).)

List of Other Managers Reporting for this Manager:




                              Form 13F SUMMARY PAGE

Report Summary:

Number of Other Included Managers:                    1

Form 13F Information Table Entry Total:              83

Form 13F Information Table Value Total:  $    1,335,600
                                         --------------
                                         (In Thousands)


List of Other Included Managers:

Provide a numbered list of the name(s) and 13F file number(s) of all
institutional investment managers with respect to which this report is filed,
other than the manager filing this report.

No.   Form 13F File Number  Name

1     028-14848             C P Management, L.L.C.
----  --------------------  ----------------------------------------------------






                                                  FORM 13F INFORMATION TABLE

          COLUMN 1               COLUMN 2     COLUMN 3  COLUMN 4      COLUMN 5        COLUMN 6  COLUMN 7        COLUMN 8
---------------------------- ---------------- --------- -------- ------------------- ---------- -------- ----------------------
                                                         VALUE    SHRS OR   SH/ PUT/ INVESTMENT  OTHER      VOTING AUTHORITY
       NAME OF ISSUER         TITLE OF CLASS    CUSIP   (x$1000)  PRN AMT   PRN CALL DISCRETION MANAGERS    SOLE    SHARED NONE
---------------------------- ---------------- --------- -------- ---------- --- ---- ---------- -------- ---------- ------ ----
                                                                                          
ALTERRA CAPITAL HOLDINGS LIM COM              G0229R108    2,379     75,539 SH       DEFINED    1            75,539      0    0
AMERICAN INTL GROUP INC      COM NEW          026874784   14,777    380,646 SH       DEFINED    1           380,646      0    0
AMERICAN RLTY CAP PPTYS INC  COM              02917T104    2,675    182,363 SH       DEFINED    1           182,363      0    0
APPLE INC                    COM              037833100   50,900    114,987 SH       DEFINED    1           114,987      0    0
BANK OF AMERICA CORPORATION  COM              060505104   10,045    824,700 SH       DEFINED    1           824,700      0    0
BARNES & NOBLE INC           COM              067774109    4,663    283,485 SH       DEFINED    1           283,485      0    0
BARNES & NOBLE INC           COM              067774109    8,225    500,000 SH  CALL DEFINED    1           500,000      0    0
BED BATH & BEYOND INC        COM              075896100   19,770    306,897 SH       DEFINED    1           306,897      0    0
BERRY PETE CO                CL A             085789105    1,359     29,360 SH       DEFINED    1            29,360      0    0
CAPITAL ONE FINL CORP        COM              14040H105   31,017    564,459 SH       DEFINED    1           564,459      0    0
CAPITAL ONE FINL CORP        COM              14040H105   27,475    500,000 SH  CALL DEFINED    1           500,000      0    0
CHENIERE ENERGY INC          COM NEW          16411R208   33,808  1,207,436 SH       DEFINED    1         1,207,436      0    0
CITIGROUP INC                COM NEW          172967424   52,840  1,194,386 SH       DEFINED    1         1,194,386      0    0
CLEARWIRE CORP NEW           CL A             18538Q105   93,661 28,907,625 SH       DEFINED    1        28,907,625      0    0
COACH INC                    COM              189754104    1,465     29,307 SH       DEFINED    1            29,307      0    0
COMMONWEALTH REIT            COM SH BEN INT   203233101    5,627    250,750 SH       DEFINED    1           250,750      0    0
CONSTELLATION BRANDS INC     CL A             21036P108   11,910    250,000 SH  CALL DEFINED    1           250,000      0    0
COPANO ENERGY L L C          COM UNITS        217202100    2,026     50,000 SH       DEFINED    1            50,000      0    0
CORRECTIONS CORP AMER NEW    COM NEW          22025Y407    6,255    160,093 SH       DEFINED    1           160,093      0    0
COVENTRY HEALTH CARE INC     COM              222862104    4,636     98,579 SH       DEFINED    1            98,579      0    0
CYMER INC                    COM              232572107   16,836    175,100 SH       DEFINED    1           175,100      0    0
DIGITALGLOBE INC             COM NEW          25389M877    9,605    332,250 SH       DEFINED    1           332,250      0    0
DST SYS INC DEL              COM              233326107   33,811    474,410 SH       DEFINED    1           474,410      0    0
E TRADE FINANCIAL CORP       COM NEW          269246401    6,454    602,604 SH       DEFINED    1           602,604      0    0
ENDO HEALTH SOLUTIONS INC    COM              29264F205   14,001    455,154 SH       DEFINED    1           455,154      0    0
EXPRESS SCRIPTS HLDG CO      COM              30219G108   14,949    259,435 SH       DEFINED    1           259,435      0    0
FACEBOOK INC                 CL A             30303M102    4,986    194,922 SH       DEFINED    1           194,922      0    0
FERRO CORP                   COM              315405100    6,683    990,100 SH       DEFINED    1           990,100      0    0
FORD MTR CO DEL              COM PAR $0.01    345370860   30,622  2,328,701 SH       DEFINED    1         2,328,701      0    0
FOREST CITY ENTERPRISES INC  CL A             345550107    3,690    207,677 SH       DEFINED    1           207,677      0    0
FREEPORT-MCMORAN COPPER & GO COM              35671D857   13,283    401,300 SH       DEFINED    1           401,300      0    0
GARDNER DENVER INC           COM              365558105    7,511    100,000 SH       DEFINED    1           100,000      0    0
GEO GROUP INC                COM              36159R103    6,840    181,822 SH       DEFINED    1           181,822      0    0
HARRY WINSTON DIAMOND CORP   COM              41587B100   13,320    815,705 SH       DEFINED    1           815,705      0    0
HERTZ GLOBAL HOLDINGS INC    COM              42805T105   81,685  3,669,603 SH       DEFINED    1         3,669,603      0    0
HESS CORP                    COM              42809H107   10,354    144,595 SH       DEFINED    1           144,595      0    0
HILLSHIRE BRANDS CO          COM              432589109    6,219    176,919 SH       DEFINED    1           176,919      0    0
JPMORGAN CHASE & CO          COM              46625H100   42,219    889,574 SH       DEFINED    1           889,574      0    0
KINDER MORGAN INC DEL        *W EXP 05/25/201 49456B119    1,732    336,944 SH       DEFINED    1           336,944      0    0
KRAFT FOODS GROUP INC        COM              50076Q106    4,408     85,536 SH       DEFINED    1            85,536      0    0
LAS VEGAS SANDS CORP         COM              517834107   28,733    509,895 SH       DEFINED    1           509,895      0    0
LEAR CORP                    COM NEW          521865204   51,058    930,523 SH       DEFINED    1           930,523      0    0
MASCO CORP                   COM              574599106    1,418     70,000 SH       DEFINED    1            70,000      0    0
METROPCS COMMUNICATIONS INC  COM              591708102   11,345  1,040,861 SH       DEFINED    1         1,040,861      0    0
MGM RESORTS INTERNATIONAL    COM              552953101   22,604  1,718,935 SH       DEFINED    1         1,718,935      0    0
MGM RESORTS INTERNATIONAL    NOTE 4.250% 4/1  55303QAE0      553    500,000 PRN      DEFINED    1                 0      0 NONE
MONDELEZ INTL INC            CL A             609207105   16,266    531,310 SH       DEFINED    1           531,310      0    0
MOSAIC CO NEW                COM              61945C103   26,751    448,765 SH       DEFINED    1           448,765      0    0
NEW YORK TIMES CO            CL A             650111107    3,407    347,695 SH       DEFINED    1           347,695      0    0
NYSE EURONEXT                COM              629491101    4,853    125,583 SH       DEFINED    1           125,583      0    0
OCH ZIFF CAP MGMT GROUP      CL A             67551U105    6,209    664,104 SH       DEFINED    1           664,104      0    0
OFFICE DEPOT INC             COM              676220106    4,968  1,264,177 SH       DEFINED    1         1,264,177      0    0
ON ASSIGNMENT INC            COM              682159108   11,735    463,653 SH       DEFINED    1           463,653      0    0
ORACLE CORP                  COM              68389X105    8,083    250,000 SH       DEFINED    1           250,000      0    0
ORACLE CORP                  COM              68389X105   12,932    400,000 SH  CALL DEFINED    1           400,000      0    0
ORIENT-EXPRESS HOTELS LTD    CL A             G67743107   22,452  2,277,034 SH       DEFINED    1         2,277,034      0    0
OSHKOSH CORP                 COM              688239201   22,674    533,622 SH       DEFINED    1           533,622      0    0
OWENS CORNING NEW            COM              690742101   29,031    736,264 SH       DEFINED    1           736,264      0    0
PENN NATL GAMING INC         COM              707569109   10,868    199,662 SH       DEFINED    1           199,662      0    0
REXNORD CORP NEW             COM              76169B102    7,329    345,226 SH       DEFINED    1           345,226      0    0






                                                  FORM 13F INFORMATION TABLE

          COLUMN 1               COLUMN 2     COLUMN 3  COLUMN 4      COLUMN 5        COLUMN 6  COLUMN 7        COLUMN 8
---------------------------- ---------------- --------- -------- ------------------- ---------- -------- ----------------------
                                                         VALUE    SHRS OR   SH/ PUT/ INVESTMENT  OTHER      VOTING AUTHORITY
       NAME OF ISSUER         TITLE OF CLASS    CUSIP   (x$1000)  PRN AMT   PRN CALL DISCRETION MANAGERS    SOLE    SHARED NONE
---------------------------- ---------------- --------- -------- ---------- --- ---- ---------- -------- ---------- ------ ----
                                                                                          
RYMAN HOSPITALITY PPTYS INC  COM              78377T107   30,948    676,460 SH       DEFINED    1           676,460      0    0
SANDRIDGE ENERGY INC         COM              80007P307    7,101  1,347,484 SH       DEFINED    1         1,347,484      0    0
SANOFI                       RIGHT 12/31/2020 80105N113      399    222,800 SH       DEFINED    1           222,800      0    0
SAUER-DANFOSS INC            COM              804137107    7,483    128,069 SH       DEFINED    1           128,069      0    0
SAVIENT PHARMACEUTICALS INC  COM              80517Q100      659    823,242 SH       DEFINED    1           823,242      0    0
SCHULMAN A INC               COM              808194104      316     10,000 SH       DEFINED    1            10,000      0    0
SCIENTIFIC GAMES CORP        CL A             80874P109    2,786    318,455 SH       DEFINED    1           318,455      0    0
SOTHEBYS                     COM              835898107   22,582    603,646 SH       DEFINED    1           603,646      0    0
SPRINT NEXTEL CORP           COM SER 1        852061100    1,323    213,122 SH       DEFINED    1           213,122      0    0
TENNECO INC                  COM              880349105   23,300    592,715 SH       DEFINED    1           592,715      0    0
THERAVANCE INC               COM              88338T104   60,849  2,576,169 SH       DEFINED    1         2,576,169      0    0
THERAVANCE INC               NOTE 3.000% 1/1  88338TAA2    5,944  5,000,000 PRN      DEFINED    1         5,000,000      0 NONE
TOLL BROTHERS INC            COM              889478103   10,957    320,000 SH       DEFINED    1           320,000      0    0
TRW AUTOMOTIVE HLDGS CORP    COM              87264S106   20,241    368,022 SH       DEFINED    1           368,022      0    0
U S AIRWAYS GROUP INC        COM              90341W108    4,113    242,373 SH       DEFINED    1           242,373      0    0
U S G CORP                   COM NEW          903293405   14,494    548,182 SH       DEFINED    1           548,182      0    0
UNITED RENTALS INC           COM              911363109   20,002    363,873 SH       DEFINED    1           363,873      0    0
VIACOM INC NEW               CL B             92553P201   27,490    447,141 SH       DEFINED    1           447,141      0    0
VIRGIN MEDIA INC             COM              92769L101   24,340    497,048 SH       DEFINED    1           497,048      0    0
VODAFONE GROUP PLC NEW       SPONS ADR NEW    92857W209   16,060    565,500 SH       DEFINED    1           565,500      0    0
VODAFONE GROUP PLC NEW       SPONS ADR NEW    92857W209    4,260    150,000 SH  CALL DEFINED    1           150,000      0    0
VULCAN MATLS CO              COM              929160109    1,920     37,142 SH       DEFINED    1            37,142      0    0
WYNN RESORTS LTD             COM              983134107   10,043     80,242 SH       DEFINED    1            80,242      0    0