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

                                    Form 13F

                               Form 13F COVER PAGE

Report for the Calendar Year or Quarter Ended: December 31, 2009

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:    Alleghany Corporation
Address: 7 Times Square Tower, 17th Floor
         New York, NY 10036

Form 13F File Number: 28-1590

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:  Roger B. Gorham
Title: Senior Vice President
Phone: 212-752-1356

Signature, Place, and Date of Signing:


   /s/ Roger B. Gorham             New York, NY             February 12, 2010
-------------------------   --------------------------   -----------------------
      [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).)



                              Form 13F SUMMARY PAGE

Report Summary:

Number of Other Included Managers:                 2
Form 13F Information Table Entry Total:           66
Form 13F Information Table Value Total:   $  637,051
                                          (thousands)

List of Other Included Managers:

No.   Form 13F File Number                  Name
---   --------------------   --------------------------------
2                            RSUI Indemnity Company
3                            Alleghany Insurance Holdings LLC



SECURITIES AND EXCHANGE COMMISSIONS FORM 13F INFORMATION
PREPARED FOR ALLEGHANY CORPORATION
AS OF 12/31/09



           COLUMN 1             COLUMN 2     COLUMN 3 COLUMN 4       COLUMN 5          COLUMN 6    COLUMN 7    COLUMN 8
---------------------------- -------------- --------- -------- ------------------- --------------- -------- --------------
                                                                                      INVESTMENT                 VOTING
                                                                                      DISCRETION               AUTHORITY
                                                       MARKET                      ---------------          --------------
                                                        VALUE    SHRS OR  SH/ PUT/ SOLE SHRD OTHER          SOLE SHRD NONE
       NAME OF ISSUER        TITLE OF CLASS   CUSIP   (X 1000)  PRIN AMT  PRN CALL  (A)  (B)  (C)   MANAGER  (A)  (B)  (C)
---------------------------- -------------- --------- -------- ---------- --- ---- ---- ---- ----- -------- ---- ---- ----
                                                                               
AT&T INC                     COM            00206R102    1,682     60,000 SH                   X       2         X
AGILENT TECHNOLOGIES INC     COM            00846U101      932     30,000 SH                   X       2         X
ALEXANDER & BALDWIN INC      COM            014482103      685     20,000 SH                   X       2         X
AMERICAN EXPRESS CO          COM            025816109    1,418     35,000 SH                   X       2         X
APACHE CORP                  COM            037411105    7,738     75,000 SH              X            1         X
APACHE CORP                  COM            037411105   23,213    225,000 SH              X            2         X
APPLIED MATLS INC            COM            038222105      976     70,000 SH                   X       2         X
AUTODESK INC                 COM            052769106      762     30,000 SH                   X       2         X
AUTOMATIC DATA PROCESSING IN COM            053015103      856     20,000 SH                   X       2         X
BARRICK GOLD CORP            COM            067901108    4,726    120,000 SH              X            1         X
BARRICK GOLD CORP            COM            067901108   14,964    380,000 SH              X            2         X
BERKSHIRE HATHAWAY INC DEL   CLB            084670207    1,314        400 SH                   X       2         X
BOEING CO                    COM            097023105      812     15,000 SH                   X       2         X
CHEVRON CORP NEW             COM            166764100    4,620     60,000 SH              X            1         X
CHEVRON CORP NEW             COM            166764100   16,168    210,000 SH              X            2         X
CHEVRON CORP NEW             COM            166764100    2,310     30,000 SH              X            3         X
CHUBB CORP                   COM            171232101    1,475     30,000 SH                   X       2         X
CINCINNATI FINL CORP         COM            172062101   18,368    700,000 SH         X                 1         X
COCA COLA CO                 COM            191216100    1,710     30,000 SH                   X       2         X
CONOCOPHILLIPS               COM            20825C104   13,789    270,000 SH              X            1         X
CONOCOPHILLIPS               COM            20825C104   31,459    616,000 SH              X            2         X
CONOCOPHILLIPS               COM            20825C104   35,748    700,000 SH              X            3         X
COSTCO WHSL CORP NEW         COM            22160K105    1,479     25,000 SH                   X       2         X
DEERE & CO                   COM            244199105    1,623     30,000 SH                   X       2         X
DEVON ENERGY CORP NEW        COM            25179M103    9,187    125,000 SH              X            1         X
DEVON ENERGY CORP NEW        COM            25179M103   27,563    375,000 SH              X            2         X
DISNEY WALT CO               COM DISNEY     254687106    1,451     45,000 SH                   X       2         X
DOMINION RES INC VA NEW      COM            25746U109    1,946     50,000 SH              X            1         X
DOMINION RES INC VA NEW      COM            25746U109    5,838    150,000 SH              X            2         X
DU PONT EI DE NEMOURS & CO   COM            263534109    1,177     35,000 SH                   X       2         X
EMERSON ELEC CO              COM            291011104    1,491     35,000 SH                   X       2         X
EXELON CORP                  COM            30161N101    4,643     95,000 SH              X            1         X
EXELON CORP                  COM            30161N101   14,905    305,000 SH              X            2         X
EXXON MOBIL CORP             COM            30231G102    2,046     30,000 SH              X            2         X
EXXON MOBIL CORP             COM            30231G102   34,095    500,000 SH              X            3         X
FPL GROUP INC                COM            302571104    5,546    105,000 SH              X            1         X
FPL GROUP INC                COM            302571104   13,839    262,000 SH              X            2         X
FEDEX CORP                   COM            31428X106    1,252     15,000 SH                   X       2         X
GENERAL ELECTRIC CO          COM            369604103    1,135     75,000 SH                   X       2         X
GLOBAL INDS LTD              COM            379336100    9,326  1,308,000 SH              X            1         X
GLOBAL INDS LTD              COM            379336100   20,620  2,892,000 SH              X            2         X
HESS CORP                    COM            42809H107   13,613    225,000 SH              X            1         X
HESS CORP                    COM            42809H107   37,812    625,000 SH              X            2         X
HESS CORP                    COM            42809H107    9,075    150,000 SH              X            3         X
HOME DEPOT INC               COM            437076102      579     20,000 SH                   X       2         X
INTEL CORP                   COM            458140100    1,734     85,000 SH                   X       2         X
INTERNATIONAL BUSINESS MACHS COM            459200101    1,571     12,000 SH                   X       2         X
INTUIT                       COM            461202103      615     20,000 SH                   X       2         X
JOHNSON AND JOHNSON          COM            478160104    1,610     25,000 SH                   X       2         X
KELLOGG CO                   COM            487836108    1,330     25,000 SH                   X       2         X
LAUDER ESTEE COS INC         CLA            518439104    1,209     25,000 SH                   X       2         X
LILLY ELI & CO               COM            532457108    1,786     50,000 SH                   X       2         X
LOCKHEED MARTIN CORP         COM            539830109   10,172    135,000 SH              X            1         X
LOCKHEED MARTIN CORP         COM            539830109   19,968    265,000 SH              X            2         X
LOEWS CORP                   COM            540424108      727     20,000 SH                   X       2         X
MARRIOTT INTL INC NEW        CLA            571903202      964     35,382 SH                   X       2         X
MEDTRONIC INC                COM            585055106    1,759     40,000 SH                   X       2         X
MICROSOFT CORP               COM            594918104    4,115    135,000 SH              X            1         X
MICROSOFT CORP               COM            594918104   13,716    450,000 SH              X            2         X
NEWMONT MINING CORP          COM            651639106    4,021     85,000 SH              X            1         X
NEWMONT MINING CORP          COM            651639106   14,903    315,000 SH              X            2         X
NEWS CORP                    CLA            65248E104      958     70,000 SH                   X       2         X
NOBLE ENERGY INC             COM            655044105    1,424     20,000 SH                   X       2         X
NORDSTROM INC                COM            655664100    1,127     30,000 SH                   X       2         X
NOVARTIS AG                  SPONSORED ADR  66987V109    1,361     25,000 SH                   X       2         X



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SECURITIES AND EXCHANGE COMMISSIONS FORM 13F INFORMATION
PREPARED FOR ALLEGHANY CORPORATION
AS OF 12/31/09



           COLUMN 1             COLUMN 2     COLUMN 3 COLUMN 4       COLUMN 5          COLUMN 6    COLUMN 7    COLUMN 8
---------------------------- -------------- --------- -------- ------------------- --------------- -------- --------------
                                                                                      INVESTMENT                 VOTING
                                                                                      DISCRETION               AUTHORITY
                                                       MARKET                      ---------------          --------------
                                                        VALUE    SHRS OR  SH/ PUT/ SOLE SHRD OTHER          SOLE SHRD NONE
       NAME OF ISSUER        TITLE OF CLASS   CUSIP   (X 1000)  PRIN AMT  PRN CALL  (A)  (B)  (C)   MANAGER  (A)  (B)  (C)
---------------------------- -------------- --------- -------- ---------- --- ---- ---- ---- ----- -------- ---- ---- ----
                                                                               
NUSTAR ENERGY LP             UNIT COM       67058H102    4,038     72,000 SH              X            1         X
NUSTAR ENERGY LP             UNIT COM       67058H102    8,582    153,000 SH              X            2         X
OCCIDENTAL PETE CORP DEL     COM            674599105   20,338    250,000 SH              X            3         X
OLD REP INTL CORP            COM            680223104   20,080  2,000,000 SH              X            3         X
PLAINS EXPL& PRODTN CO       COM            726505100    7,911    286,000 SH              X            1         X
PLAINS EXPL& PRODTN CO       COM            726505100   20,579    744,000 SH              X            2         X
PROCTER & GAMBLE CO          COM            742718109    1,819     30,000 SH                   X       2         X
SCHLUMBERGER LTD             COM            806857108    1,627     25,000 SH                   X       2         X
SIEMENS A G                  SPONSORED ADR  826197501    1,146     12,500 SH                   X       2         X
SIGMA ALDRICH CORP           COM            826552101    1,011     20,000 SH                   X       2         X
STATE STR CORP               COM            857477103      653     15,000 SH                   X       2         X
SYSCO CORP                   COM            871829107    1,118     40,000 SH                   X       2         X
3M CO                        COM            88579Y101    1,819     22,000 SH                   X       2         X
TRICO MARINE SERVICES INC    COM NEW        896106200    1,635    360,000 SH              X            1         X
TRICO MARINE SERVICES INC    COM NEW        896106200    3,927    865,000 SH              X            2         X
US BANCORP DEL               COM NEW        902973304      563     25,000 SH                   X       2         X
WAL MART STORES INC          COM            931142103    1,871     35,000 SH                   X       2         X
WASHINGTON POST CO           CLB            939640108      879      2,000 SH                   X       2         X
WELLS FARGO & CO NEW         COM            949746101      540     20,000 SH                   X       2         X
WILLIAMS CO INC DEL          COM            969457100    9,274    440,000 SH              X            1         X
WILLIAMS CO INC DEL          COM            969457100   18,129    860,000 SH              X            2         X
WILLIAMS CO INC DEL          COM            969457100    2,108    100,000 SH              X            3         X
ZENITH NATL INS CORP         COM            989390109    4,018    135,000 SH              X            1         X
ZENITH NATL INS CORP         COM            989390109   12,350    415,000 SH              X            2         X
GRAND TOTAL                                            637,051 19,997,282



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