SEC FORM 13F-HR

The Securities and Exchange Commission has not necessarily reviewed the information in this filing and has not determined if it is accurate and complete.
The reader should not assume that the information is accurate and complete.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM 13F

FORM 13F COVER PAGE

OMB APPROVAL
OMB Number:3235-0006
Expires:Oct 31, 2018
Estimated average burden
hours per response:23.8

Report for the Calendar Year or Quarter Ended:09-30-2013
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:COWEN GROUP, INC.
Address:599 LEXINGTON AVENUE, 20TH FLOOR
NEW YORK, NY  10022
Form 13F File Number:028-14571

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:Owen Littman
Title:General Counsel
Phone:212-201-4841
Signature, Place, and Date of Signing:
/s/ Owen LittmanNew YorkNY11-14-2013
[Signature][City, State][Date]
Report Type (Check only one.):
X13F 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:3
Form 13F Information Table Entry Total:222
Form 13F Information Table Value Total:666,951
(thousands)
List of Other Included Managers:
Provide a numbered list of the 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.]
No.Form 13F File NumberName
1028-10674RAMIUS ADVISORS LLC
2028-14361Ramius Alternative Solutions LLC
3028-04125COWEN & COMPANY, LLC

SEC FORM 13-F Information Table

The Securities and Exchange Commission has not necessarily reviewed the information in this filing and has not determined if it is accurate and complete.
The reader should not assume that the information is accurate and complete.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM 13F

FORM 13F INFORMATION TABLE

OMB APPROVAL
OMB Number:3235-0006
Expires:Oct 31, 2018
Estimated average burden
hours per response:23.8

COLUMN 1COLUMN 2COLUMN 3COLUMN 4COLUMN 5COLUMN 6COLUMN 7COLUMN 8
VALUESHRS ORSH/PUT/INVESTMENTOTHERVOTING AUTHORITY
NAME OF ISSUERTITLE OF CLASSCUSIP(x$1000)PRN AMTPRNCALLDISCRETIONMANAGERSOLESHAREDNONE
FORTRESS PAPER LTD-CL ACS34958R1012,627384,898SH DFND1384,89800
ACCESS MIDSTREAM PARTNERS LUNIT00434L1092425,000SH DFND15,00000
ACHILLION PHARMACEUTICALS INCOM00448Q2010100SH DFND210000
ACHILLION PHARMACEUTICALS INCOM00448Q201302100,000SHCallDFND2000
ACTIVE NETWORK INCCOM00506D10028720,100SH DFND220,10000
ACTIVE NETWORK INCCOM00506D1003,184222,500SH DFND1222,50000
ADOBE SYS INCCOM00724F10178415,100SHCallDFND2000
AGILENT TECHNOLOGIES INCCOM00846U1014619,000SH DFND19,00000
AMERICAN RLTY CAP PPTYS INCCOM02917T1042,001164,000SHCallDFND2000
AMYRIS INCCOM03236M1019942,800SH DFND142,80000
APPLIED MATLS INCCOM0382221051,4908,500,000SHPutDFND18,500,00000
ARIAD PHARMACEUTICALS INCCOM04033A10082845,000SH DFND145,00000
ASTEX PHARMACEUTICALS INCCOM04624B1035,340628,972SH DFND1628,97200
AURICO GOLD INCCOM05155C1054010,600SH DFND110,60000
B2GOLD CORPCOM11777Q2096225,000SH DFND125,00000
BANK OF AMERICA CORPORATIONCOM0605051043602,610,000SHCallDFND1000
BAXTER INTL INCCOM07181310998515,000SH DFND215,00000
BAXTER INTL INCCOM0718131091,31420,000SHPutDFND220,00000
BELO CORPCOM SER A0805551053332,430,000SHCallDFND1000
BIOGEN IDEC INCCOM09062X1038433,500SHCallDFND2000
BLACKBERRY LTDCOM09228F1031,64720,730,000SHPutDFND120,730,00000
BOISE INCCOM09746Y1051,260100,000SH DFND1100,00000
BROADCOM CORPCL A11132010739015,000SHCallDFND2000
BUCKEYE PARTNERS L PUNIT LTD PARTN1182301011,55623,750SH DFND123,75000
CAPITAL ONE FINL CORPCOM14040H1053475,050SH DFND15,05000
CAPITALSOURCE INCCOM14055X10221017,700SH DFND217,70000
CARNIVAL CORPPAIRED CTF14365830065320,000SHCallDFND2000
CF INDS HLDGS INCCOM1252691004742,250SH DFND12,25000
CISCO SYS INCCOM17275R1021,03644,200SH DFND244,20000
CISCO SYS INCCOM17275R1021,03644,200SHPutDFND244,20000
COMPUWARE CORPCOM2056381091,912170,873SH DFND1170,87300
COOPER TIRE & RUBR COCOM2168311073201,040,000SHPutDFND11,040,00000
COOPER TIRE & RUBR COCOM21683110741713,537SH DFND213,53700
COOPER TIRE & RUBR COCOM21683110761920,100SHPutDFND220,10000
COOPER TIRE & RUBR COCOM2168311073,66211,890,000SHCallDFND1000
COPART INCCOM21720410650115,750SH DFND115,75000
COWEN GROUP INC NEWCL A2236221015,4841,594,292SH DFND11,594,29200
CROWN HOLDINGS INCCOM22836810684620,000SHCallDFND2000
CYPRESS SEMICONDUCTOR CORPCOM23280610923425,000SHPutDFND225,00000
CYPRESS SEMICONDUCTOR CORPCOM23280610949152,500SHCallDFND2000
DELL INCCOM24702R10110700SH DFND270000
DELL INCCOM24702R1011,1918,660,000SHCallDFND1000
DELL INCCOM24702R10113,268964,900SH DFND1964,90000
ELAN PLCADR28413120831820,398SH DFND220,39800
ELAN PLCADR2841312084082,620,000SHCallDFND1000
ELAN PLCADR28413120810,900699,620SH DFND1699,62000
ENERGY TRANSFER EQUITY L PCOM UT LTD PTN29273V10093214,175SH DFND114,17500
ENTERPRISE PRODS PARTNERS LCOM2937921071,36622,375SH DFND122,37500
EQUINIX INCCOM NEW29444U5023,00916,382SH DFND116,38200
EXPEDIA INC DELCOM NEW30212P3033637,000SH DFND27,00000
EXPEDIA INC DELCOM NEW30212P3031,29525,000SHPutDFND225,00000
EXPEDIA INC DELCOM NEW30212P3033,63270,100SHCallDFND2000
EXXON MOBIL CORPCOM30231G1022562,971SH DFND12,97100
FACEBOOK INCCL A30303M1022014,000SH DFND24,00000
FACEBOOK INCCL A30303M10250210,000SHPutDFND210,00000
FAMILY DLR STORES INCCOM3070001092884,000SH DFND24,00000
FAMILY DLR STORES INCCOM30700010972010,000SHCallDFND2000
FAMILY DLR STORES INCCOM30700010972010,000SHPutDFND210,00000
FEDERAL SIGNAL CORPCOM31385510884665,708SH DFND165,70800
FMC TECHNOLOGIES INCCOM30249U1012,03028,300SHCallDFND2000
FORTINET INCCOM34959E10920310,000SHCallDFND2000
FORTINET INCCOM34959E10981040,000SH DFND240,00000
GENCORP INCCOM36868210036122,500SH DFND122,50000
GENESIS ENERGY L PUNIT LTD PARTN37192710450110,000SH DFND110,00000
GLOBECOMM SYSTEMS INCCOM37956X1036,557468,015SH DFND1468,01500
GOLD FIELDS LTD NEWSPONSORED ADR38059T1066113,300SH DFND113,30000
GOLDEN MINERALS COCOM3811191064547,800SH DFND147,80000
GOLDEN STAR RES LTD CDACOM38119T1041331,600SH DFND131,60000
GOOGLE INCCL A38259P5089641,100SH DFND11,10000
GROUPON INCCOM CL A39947310773465,500SHCallDFND2000
GROUPON INCCOM CL A3994731071,121100,000SHPutDFND2100,00000
GROUPON INCCOM CL A3994731071,906170,000SH DFND2170,00000
HALLIBURTON COCOM40621610114,460300,300SHCallDFND2000
HARMONY GOLD MNG LTDSPONSORED ADR4132163005917,400SH DFND117,40000
HARRIS TEETER SUPERMARKETS ICOM4145851093497,088SH DFND27,08800
HARSCO CORPCOM41586410749820,000SHCallDFND2000
HEALTH MGMT ASSOC INC NEWCL A42193310251240,000SHCallDFND2000
HEALTH MGMT ASSOC INC NEWCL A4219331022,307180,200SHPutDFND2180,20000
HERBALIFE LTDCOM USD SHSG4412G10187712,575SH DFND112,57500
HI-TECH PHARMACAL INCCOM42840B1012,13649,511SH DFND149,51100
HOUSTON AMERN ENERGY CORPCOM44183U1001138,000SH DFND138,00000
IAMGOLD CORPCOM4509131085711,900SH DFND111,90000
IMMUNOGEN INCCOM45253H10174043,500SH DFND243,50000
IMMUNOGEN INCCOM45253H1011,59593,700SHPutDFND293,70000
INERGY L PUNIT LTD PTNR45661510335525,750SH DFND125,75000
INTERNATIONAL BUSINESS MACHSCOM4592001018334,500SH DFND14,50000
IRON MTN INCCOM4628461061,10840,999SH DFND140,99900
ISHARESMSCI CDA ETF46428650928310,000SH DFND110,00000
ISHARESRUS 1000 VAL ETF46428759842,258490,237SH DFND3490,23700
ISHARESRUSSELL 2000 ETF4642876558107,600SH DFND17,60000
JOHNSON & JOHNSONCOM4781601043,03435,000SH DFND235,00000
JOHNSON & JOHNSONCOM4781601043,03435,000SHPutDFND235,00000
JONES GROUP INCCOM48020T10142728,445SH DFND128,44500
JONES GROUP INCCOM48020T10182655,000SHPutDFND255,00000
JONES GROUP INCCOM48020T1019616,400,000SHPutDFND16,400,00000
JONES GROUP INCCOM48020T1011,00667,000SHCallDFND2000
KIOR INCCL A4972171093111,100SH DFND111,10000
LAMAR ADVERTISING COCL A51281510184718,000SH DFND118,00000
LEAP WIRELESS INTL INCCOM NEW5218633083,57222,610,000SHCallDFND1000
LEAP WIRELESS INTL INCCOM NEW5218633087,32846,380,000SHPutDFND146,380,00000
LEVEL 3 COMMUNICATIONS INCCOM NEW52729N30836013,500SH DFND113,50000
LIBERTY GLOBAL PLCSHS CL CG5480U1204,78663,455SH DFND163,45500
LIFE TECHNOLOGIES CORPCOM53217V1091,49720,000SH DFND220,00000
LIFE TECHNOLOGIES CORPCOM53217V1094,49060,000SHPutDFND260,00000
LIFE TECHNOLOGIES CORPCOM53217V1095,14868,800SHCallDFND2000
LIFE TECHNOLOGIES CORPCOM53217V10928,455380,268SH DFND1380,26800
LINN ENERGY LLCUNIT LTD LIAB5360201002,65710,250,000SHCallDFND1000
LINN ENERGY LLCUNIT LTD LIAB5360201003,27212,620,000SHPutDFND112,620,00000
LOWES COS INCCOM5486611071,69035,500SHCallDFND2000
LYONDELLBASELL INDUSTRIES NSHS - A -N537451007,660104,600SHCallDFND2000
MAGELLAN MIDSTREAM PRTNRS LPCOM UNIT RP LP5590801061,88833,460SH DFND133,46000
MAKO SURGICAL CORPCOM56087910888530,000SHCallDFND2000
MAKO SURGICAL CORPCOM5608791081,6235,500,000SHPutDFND15,500,00000
MAKO SURGICAL CORPCOM5608791082,61888,727SH DFND188,72700
MALLINCKRODT PUB LTD COSHSG5785G1072,20449,989SH DFND149,98900
MANNKIND CORPCOM56400P201519,000SH DFND29,00000
MANNKIND CORPCOM56400P20132857,500SHCallDFND2000
MICROSOFT CORPCOM59491810490127,085SH DFND127,08500
MOLEX INCCL A6085542005,716149,325SH DFND1149,32500
MONDELEZ INTL INCCL A6092071052839,000SH DFND19,00000
MONSTER WORLDWIDE INCCOM6117421077216,200SH DFND116,20000
MYLAN INCCOM6285301072,67270,000SHPutDFND270,00000
NABORS INDUSTRIES LTDSHSG6359F10351432,000SH DFND132,00000
NEUROCRINE BIOSCIENCES INCCOM64125C10911310,000SHCallDFND2000
NEW GOLD INC CDACOM6445351066210,300SH DFND110,30000
NEWS CORP NEWCL B65249B20844427,000SH DFND127,00000
NII HLDGS INCCL B NEW62913F2016410,600SHCallDFND2000
NII HLDGS INCCL B NEW62913F20159998,600SH DFND298,60000
NII HLDGS INCCL B NEW62913F2011,090179,550SH DFND1179,55000
NOBLE CORPORATION BAARNAMEN -AKTH5833N1031,51040,000SHPutDFND240,00000
NOBLE CORPORATION BAARNAMEN -AKTH5833N10314,149374,600SHCallDFND2000
NORTHWEST PIPE COCOM6677461011,52446,345SH DFND146,34500
NUANCE COMMUNICATIONS INCCOM67020Y10095551,100SH DFND251,10000
NUANCE COMMUNICATIONS INCCOM67020Y1002,421129,590SH DFND1129,59000
NUANCE COMMUNICATIONS INCCOM67020Y1002,52213,500,000SHPutDFND113,500,00000
NV ENERGY INCCOM67073Y1065,836247,180SH DFND1247,18000
NYSE EURONEXTCOM62949110117,393414,314SH DFND1414,31400
OCCIDENTAL PETE CORP DELCOM6745991052532,700SHCallDFND2000
OIL STS INTL INCCOM6780261051,16411,250SH DFND111,25000
ONCOTHYREON INCCOM682324108412200,000SH DFND1200,00000
ONEOK PARTNERS LPUNIT LTD PARTN68268N10363712,015SH DFND112,01500
ONYX PHARMACEUTICALS INCCOM6833991091,110890,000SHPutDFND1890,00000
ONYX PHARMACEUTICALS INCCOM6833991094,80138,500SHCallDFND2000
ONYX PHARMACEUTICALS INCCOM68339910921,069168,961SH DFND1168,96100
ONYX PHARMACEUTICALS INCCOM68339910925,43820,400,000SHCallDFND1000
OPTIMER PHARMACEUTICALS INCCOM68401H10402,000SHCallDFND2000
OPTIMER PHARMACEUTICALS INCCOM68401H10417113,581SH DFND213,58100
PACKAGING CORP AMERCOM6951561095,01787,900SHCallDFND2000
PACTERA TECHNOLOGY INTL LTDSPONSORED ADR69525510970712,000,000SHPutDFND112,000,00000
PACWEST BANCORP DELCOM6952631032537,376SH DFND27,37600
PARKERVISION INCCOM7013541029428,000SH DFND128,00000
PERRIGO COCOM7142901031,8381,490,000SHPutDFND11,490,00000
PERRIGO COCOM7142901036,8355,540,000SHCallDFND1000
PLAINS ALL AMERN PIPELINE LUNIT LTD PARTN7265031051,21523,070SH DFND123,07000
POLYCOM INCCOM73172K10454650,000SHPutDFND250,00000
POLYCOM INCCOM73172K10461256,000SH DFND256,00000
POWERSHARES ETF TRUST IISENIOR LN PORT73936Q76915,782639,283SH DFND3639,28300
PROSHARES TR IIULTRASHORT YEN N74347W56978512,620SH DFND112,62000
QUESTCOR PHARMACEUTICALS INCCOM74835Y1015108,800SHCallDFND2000
RADISYS CORPCOM7504591099128,400SH DFND128,40000
REGENCY ENERGY PARTNERS L PCOM UNITS L P75885Y10728610,000SH DFND110,00000
REPLIGEN CORPCOM75991610977670,000SHCallDFND2000
REPROS THERAPEUTICS INCCOM NEW76028H20958721,900SH DFND221,90000
REPROS THERAPEUTICS INCCOM NEW76028H20965424,400SHPutDFND224,40000
RESMED INCCOM76115210766012,500SHPutDFND212,50000
RICHMONT MINES INCCOM76547T1067452,300SH DFND152,30000
RIVERBED TECHNOLOGY INCCOM76857310714610,000SH DFND210,00000
RLJ ENTMT INCCOM74965F1047413,503SH DFND113,50300
ROCKWOOD HLDGS INCCOM7744151033,73355,800SHCallDFND2000
RUBICON MINERALS CORPCOM7809111032116,800SH DFND116,80000
RUE21 INCCOM781295100401,000SH DFND21,00000
RUE21 INCCOM7812951002,0455,070,000SHPutDFND15,070,00000
SANCHEZ ENERGY CORPCOM79970Y10577929,490SH DFND129,49000
SCHWAB CHARLES CORP NEWCOM8085131051,16254,950SH DFND154,95000
SCIENTIFIC GAMES CORPCL A80874P1094,741293,201SH DFND1293,20100
SEALED AIR CORP NEWCOM81211K10059822,000SHPutDFND222,00000
SEALED AIR CORP NEWCOM81211K10063923,500SH DFND223,50000
SEALED AIR CORP NEWCOM81211K1001,02037,500SHCallDFND2000
SEATTLE GENETICS INCCOM812578102882,000SH DFND22,00000
SEATTLE GENETICS INCCOM8125781021,21827,800SHPutDFND227,80000
SHFL ENTMT INCCOM78423R1052,655115,598SH DFND1115,59800
SIBANYE GOLD LTDSPONSORED ADR825724206645123,750SH DFND1123,75000
SIGA TECHNOLOGIES INCCOM8269171061,035270,914SH DFND1270,91400
SLM CORPCOM78442P1069,178368,600SHCallDFND2000
SMITHFIELD FOODS INCCOM832248108035,600SHPutDFND235,60000
SMITHFIELD FOODS INCCOM8322481080382,500SHCallDFND2000
SMITHFIELD FOODS INCCOM83224810826,67378,450,000SHCallDFND1000
SOURCEFIRE INCCOM83616T1084866,400SHCallDFND2000
SPDR GOLD TRUSTGOLD SHS78463V1072582,015SH DFND12,01500
SPDR S&P 500 ETF TRTR UNIT78462F1038745,200SH DFND15,20000
SPDR S&P 500 ETF TRTR UNIT78462F10356,11633,400,000SHPutDFND133,400,00000
SPDR S&P MIDCAP 400 ETF TRUTSER1 S&PDCRP78467Y10797,431430,482SH DFND3430,48200
SPDR SERIES TRUSTBRC HGH YLD BD78464A4171,12628,250SH DFND128,25000
SPRINT CORPCOM SER 185207U1051,23819,910,000SHCallDFND1000
STERLING BANCORPCOM85915810756541,157SH DFND141,15700
STERLING FINL CORP WASHCOM NEW8593193032548,875SH DFND28,87500
SUBURBAN PROPANE PARTNERS LUNIT LTD PARTN86448210466914,297SH DFND114,29700
SUNESIS PHARMACEUTICALS INCCOM NEW8673286012,244452,517SH DFND2452,51700
SUNOCO LOGISTICS PRTNRS L PCOM UNITS86764L1081,74526,259SH DFND126,25900
SYNTA PHARMACEUTICALS CORPCOM87162T20622135,000SHCallDFND2000
TANZANIAN ROYALTY EXPL CORPCOM87600U1043112,300SH DFND112,30000
TELEPHONE & DATA SYS INCCOM NEW87943382969223,428SH DFND123,42800
TESORO CORPCOM8816091014,08192,800SH DFND192,80000
THE ADT CORPORATIONCOM00101J10695523,490SH DFND123,49000
THRESHOLD PHARMACEUTICAL INCCOM NEW8858072069320,000SH DFND120,00000
TIMMINS GOLD CORPCOM88741P1032615,600SH DFND115,60000
TRANSITION THERAPEUTICS INCCOM NEW89371620915036,600SH DFND236,60000
TRANSOCEAN LTDREG SHSH8817H1001,90242,750SH DFND142,75000
TURQUOISE HILL RES LTDCOM9004351087517,000SH DFND217,00000
U S AIRWAYS GROUP INCCOM90341W1081,90910,070,000SHPutDFND110,070,00000
UNITEDHEALTH GROUP INCCOM91324P1022012,800SH DFND22,80000
VANGUARD INTL EQUITY INDEX FFTSE EMR MKT ETF92204285813,008324,110SH DFND3324,11000
VERTEX PHARMACEUTICALS INCCOM92532F1001,36518,000SH DFND218,00000
VERTEX PHARMACEUTICALS INCCOM92532F1003,12441,200SHPutDFND241,20000
VIRNETX HLDG CORPCOM92823T1082,945144,369SH DFND1144,36900
VISTA GOLD CORPCOM NEW9279263034393,800SH DFND193,80000
VIVUS INCCOM92855110039542,500SH DFND242,50000
VIVUS INCCOM9285511001,349145,000SHCallDFND2000
VIVUS INCCOM9285511002,072222,759SH DFND1222,75900
WAL-MART STORES INCCOM9311421035647,625SH DFND17,62500
WALTER INVT MGMT CORPCOM93317W10244811,335SH DFND111,33500
WILLIAMS COS INC DELCOM96945710045512,500SH DFND112,50000