SECURITIES AND EXCHANGE COMMISSION

FORM 13F-HR Initial quarterly Form 13F holdings report filed by institutional managers

Filing Date: 2015-11-16 | Period of Report: 2015-09-30 SEC Accession No. 0001172661-15-002063

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FILER Rock Springs Capital Management LP Mailing Address Business Address 650 SOUTH EXETER 650 SOUTH EXETER CIK:1595725| IRS No.: 800944416 | State of Incorp.:DE | Fiscal Year End: 1231 STREET STREET Type: 13F-HR | Act: 34 | File No.: 028-16048 | Film No.: 151233257 BALTIMORE MD 21202 BALTIMORE MD 21202 4102200129

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FORM 13F COVER PAGE Report for the Calendar Year or Quarter Ended: 09-30-2015 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: Rock Springs Capital Management LP Address: 650 South Exeter Street Baltimore, MD 21202 Form 13F File Number: 028-16048

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: Evans Apeadu Title: Chief Financial Officer/Chief Compliance Officer Phone: 410-220-0129

Signature, Place, and Date of Signing: /s/ Evans Apeadu Baltimore, MARYLAND 11-16-2015 [Signature] [City, State] [Date]

Report Type (Check only one.): ☒ 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: 0 Form 13F Information table Entry Total: 121 Form 13F Information table Value Total: 1231971 (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.]

NONE

Copyright © 2013 www.secdatabase.com. All Rights Reserved. Please Consider the Environment Before Printing This Document OMB APPROVAL UNITED STATES SECURITIES AND EXCHANGE COMMISSION OMB Number: 3235-0006 Washington, D.C. 20549 Expires: July 31, 2015 Estimated average burden FORM 13F hours per response: 23.8

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 MANAGER SOLE SHARED NONE ABBVIE INC COM 00287Y109 40,613 746,423 SH SOLE 746,423 0 0 ACADIA HEALTHCARE COMPANY IN COM 00404A109 53,811 812,000 SH SOLE 812,000 0 0 ACHILLION PHARMACEUTICALS IN COM 00448Q201 7,774 1,125,000 SH SOLE 1,125,000 0 0 ADAPTIMMUNE THERAPEUTICS PLC SPONDS ADR 00653A107 9,051 756,100 SH SOLE 756,100 0 0 ADEPTUS HEALTH INC CL A 006855100 14,375 178,000 SH SOLE 178,000 0 0 ADURO BIOTECH INC COM 00739L101 8,039 415,000 SH SOLE 415,000 0 0 ADVAXIS INC COM NEW 007624208 3,448 337,000 SH SOLE 337,000 0 0 AETNA INC NEW COM 00817Y108 42,232 386,000 SH SOLE 386,000 0 0 AIMMUNE THERAPEUTICS INC COM 00900T107 5,064 200,000 SH SOLE 200,000 0 0 INC COM 015351109 26,899 172,000 SH SOLE 172,000 0 0 PLC SHS G0177J108 34,248 126,000 SH SOLE 126,000 0 0 ALLERGAN PLC PFD CONV SER A G0177J116 4,728 5,000 SH SOLE 5,000 0 0 INC COM 031162100 11,515 83,250 SH SOLE 83,250 0 0 AMICUS THERAPEUTICS INC COM 03152W109 6,365 455,000 SH SOLE 455,000 0 0 ANACOR PHARMACEUTICALS INC COM 032420101 10,123 86,000 SH SOLE 86,000 0 0 ANTHEM INC COM 036752103 12,250 87,500 SH SOLE 87,500 0 0 ANTHERA PHARMACEUTICALS INC COM NEW 03674U201 2,436 400,000 SH SOLE 400,000 0 0 ARATANA THERAPEUTICS INC COM 03874P101 4,103 485,000 SH SOLE 485,000 0 0 ARDELYX INC COM 039697107 11,776 681,500 SH SOLE 681,500 0 0 ASCENDIS PHARMA A S SPONSORED ADR 04351P101 4,779 270,000 SH SOLE 270,000 0 0 ASSEMBLY BIOSCIENCES INC COM 045396108 3,547 371,000 SH SOLE 371,000 0 0 ATHENAHEALTH INC COM 04685W103 5,067 38,000 SH SOLE 38,000 0 0 ATYR PHARMA INC COM 002120103 3,991 388,996 SH SOLE 388,996 0 0 BIODEL INC COM NEW 09064M204 1,760 4,000,000 SH SOLE 4,000,000 0 0 INC COM 09062X103 11,278 38,650 SH SOLE 38,650 0 0 BIOMARIN PHARMACEUTICAL INC COM 09061G101 5,319 50,500 SH SOLE 50,500 0 0 BLUEBIRD BIO INC COM 09609G100 3,850 45,000 SH SOLE 45,000 0 0 CARDIOME PHARMA CORP COM NO PAR 14159U301 10,044 1,190,000 SH SOLE 1,190,000 0 0 CASTLIGHT HEALTH INC CL B 14862Q100 4,200 1,000,000 SH SOLE 1,000,000 0 0 CELGENE CORP COM 151020104 21,418 198,000 SH SOLE 198,000 0 0 CERULEAN PHARMA INC COM 15708Q105 2,288 625,000 SH SOLE 625,000 0 0 CHIASMA INC COM 16706W102 10,387 522,500 SH SOLE 522,500 0 0 CHINA CORD BLOOD CORP SHS G21107100 5,298 880,000 SH SOLE 880,000 0 0 CIDARA THERAPEUTICS INC COM 171757107 3,498 275,000 SH SOLE 275,000 0 0 CIGNA CORPORATION COM 125509109 16,472 122,000 SH SOLE 122,000 0 0 COHERUS BIOSCIENCES INC COM 19249H103 5,711 285,000 SH SOLE 285,000 0 0 COLLEGIUM PHARMACEUTICAL INC COM 19459J104 21,986 994,400 SH SOLE 994,400 0 0 COMPUGEN LTD ORD M25722105 2,714 525,000 SH SOLE 525,000 0 0 CONNECTURE INC COM 20786J106 1,664 365,000 SH SOLE 365,000 0 0 COOPER COS INC COM NEW 216648402 9,214 61,900 SH SOLE 61,900 0 0 CVS HEALTH CORP COM 126650100 11,578 120,000 SH SOLE 120,000 0 0 DAVITA HEALTHCARE PARTNERS I COM 23918K108 8,828 122,050 SH SOLE 122,050 0 0 DBV TECHNOLOGIES S A SPONSORED ADR 23306J101 890 25,000 SH SOLE 25,000 0 0 DERMIRA INC COM 24983L104 7,002 300,001 SH SOLE 300,001 0 0 DYAX CORP COM 26746E103 2,186 114,500 SH SOLE 114,500 0 0

Copyright © 2013 www.secdatabase.com. All Rights Reserved. Please Consider the Environment Before Printing This Document DYNAVAX TECHNOLOGIES CORP COM NEW 268158201 3,681 150,000 SH SOLE 150,000 0 0 EGALET CORP COM 28226B104 3,954 300,000 SH SOLE 300,000 0 0 ENDOCHOICE HLDGS INC COM 29272U103 6,543 576,000 SH SOLE 576,000 0 0 ENVISION HEALTHCARE HLDGS IN COM 29413U103 20,970 570,000 SH SOLE 570,000 0 0 EPIZYME INC COM 29428V104 3,987 310,000 SH SOLE 310,000 0 0 FIBROGEN INC COM 31572Q808 4,165 190,000 SH SOLE 190,000 0 0 FIVE PRIME THERAPEUTICS INC COM 33830X104 1,847 120,000 SH SOLE 120,000 0 0 GALAPAGOS NV SPON ADR 36315X101 8,549 210,000 SH SOLE 210,000 0 0 GENOCEA BIOSCIENCES INC COM 372427104 4,453 650,000 SH SOLE 650,000 0 0 INC COM 375558103 25,284 257,500 SH SOLE 257,500 0 0 GLOBAL BLOOD THERAPEUTICS IN COM 37890U108 2,530 60,000 SH SOLE 60,000 0 0 GW PHARMACEUTICALS PLC ADS 36197T103 7,812 85,500 SH SOLE 85,500 0 0 HCA HOLDINGS INC COM 40412C101 37,945 490,500 SH SOLE 490,500 0 0 HEALTHSOUTH CORP COM NEW 421924309 12,950 337,500 SH SOLE 337,500 0 0 HEARTWARE INTL INC COM 422368100 14,281 273,000 SH SOLE 273,000 0 0 IDEXX LABS INC COM 45168D104 8,353 112,500 SH SOLE 112,500 0 0 INCYTE CORP COM 45337C102 12,467 113,000 SH SOLE 113,000 0 0 INFINITY PHARMACEUTICALS INC COM 45665G303 1,817 215,000 SH SOLE 215,000 0 0 INOVALON HLDGS INC COM CL A 45781D101 14,269 685,000 SH SOLE 685,000 0 0 INSMED INC COM PAR $.01 457669307 6,778 365,000 SH SOLE 365,000 0 0 INSYS THERAPEUTICS INC NEW COM NEW 45824V209 8,766 308,000 SH SOLE 308,000 0 0 INTERCEPT PHARMACEUTICALS IN COM 45845P108 5,390 32,500 SH SOLE 32,500 0 0 INTERSECT ENT INC COM 46071F103 5,558 237,500 SH SOLE 237,500 0 0 INTRA CELLULAR THERAPIES INC COM 46116X101 7,207 180,000 SH SOLE 180,000 0 0 INTUITIVE SURGICAL INC COM NEW 46120E602 16,545 36,000 SH SOLE 36,000 0 0 INVITAE CORP COM 46185L103 3,682 510,000 SH SOLE 510,000 0 0 PLC SHS USD G50871105 6,840 51,500 SH SOLE 51,500 0 0 JUNO THERAPEUTICS INC COM 48205A109 8,016 197,001 SH SOLE 197,001 0 0 KINDRED BIOSCIENCES INC COM 494577109 1,430 275,000 SH SOLE 275,000 0 0 KITE PHARMA INC COM 49803L109 5,095 91,500 SH SOLE 91,500 0 0 LILLY ELI & CO COM 532457108 19,458 232,500 SH SOLE 232,500 0 0 MACROGENICS INC COM 556099109 4,670 218,000 SH SOLE 218,000 0 0 MCKESSON CORP COM 58155Q103 12,952 70,000 SH SOLE 70,000 0 0 MEDICINES CO COM 584688105 22,586 595,000 SH SOLE 595,000 0 0 MEDNAX INC COM 58502B106 9,599 125,000 SH SOLE 125,000 0 0 NABRIVA THERAPEUTICS AG SPONSORED ADR 62957M104 3,082 324,400 SH SOLE 324,400 0 0 NEUROCRINE BIOSCIENCES INC COM 64125C109 14,881 374,000 SH SOLE 374,000 0 0 NIVALIS THERAPEUTICS INC COM 65481J109 6,342 489,000 SH SOLE 489,000 0 0 NOVADAQ TECHNOLOGIES INC COM 66987G102 5,632 540,000 SH SOLE 540,000 0 0 NOVAVAX INC COM 670002104 5,055 715,000 SH SOLE 715,000 0 0 OREXIGEN THERAPEUTICS INC COM 686164104 3,482 1,650,000 SH SOLE 1,650,000 0 0 OTONOMY INC COM 68906L105 5,713 320,800 SH SOLE 320,800 0 0 PACIRA PHARMACEUTICALS INC COM 695127100 6,905 168,000 SH SOLE 168,000 0 0 PENUMBRA INC COM 70975L107 7,820 195,000 SH SOLE 195,000 0 0 INC COM 717081103 23,872 760,000 SH SOLE 760,000 0 0 PRA HEALTH SCIENCES INC COM 69354M108 9,824 253,000 SH SOLE 253,000 0 0 PROTHENA CORP PLC SHS G72800108 11,244 248,000 SH SOLE 248,000 0 0 PTC THERAPEUTICS INC COM 69366J200 1,147 42,960 SH SOLE 42,960 0 0 PUMA BIOTECHNOLOGY INC COM 74587V107 1,198 15,900 SH SOLE 15,900 0 0 RADIUS HEALTH INC COM NEW 750469207 38,814 560,000 SH SOLE 560,000 0 0 RAPTOR PHARMACEUTICAL CORP COM 75382F106 1,845 305,000 SH SOLE 305,000 0 0 REGENERON PHARMACEUTICALS COM 75886F107 5,117 11,000 SH SOLE 11,000 0 0 RELYPSA INC COM 759531106 4,665 252,000 SH SOLE 252,000 0 0 RETROPHIN INC COM 761299106 13,856 683,900 SH SOLE 683,900 0 0

Copyright © 2013 www.secdatabase.com. All Rights Reserved. Please Consider the Environment Before Printing This Document ROKA BIOSCIENCE INC COM 775431109 485 250,000 SH SOLE 250,000 0 0 RTI SURGICAL INC COM 74975N105 10,565 1,860,000 SH SOLE 1,860,000 0 0 SCYNEXIS INC COM 811292101 3,422 470,000 SH SOLE 470,000 0 0 SERES THERAPEUTICS INC COM 81750R102 5,335 180,000 SH SOLE 180,000 0 0 SPARK THERAPEUTICS INC COM 84652J103 1,907 45,700 SH Put SOLE 45,700 0 0 SPARK THERAPEUTICS INC COM 84652J103 20,865 500,000 SH SOLE 500,000 0 0 ST JUDE MED INC COM 790849103 33,438 530,000 SH SOLE 530,000 0 0 TANDEM DIABETES CARE INC COM 875372104 4,779 542,500 SH SOLE 542,500 0 0 TEAM HEALTH HOLDINGS INC COM 87817A107 17,019 315,000 SH SOLE 315,000 0 0 TESARO INC COM 881569107 9,063 226,000 SH SOLE 226,000 0 0 TEVA PHARMACEUTICAL INDS LTD ADR 881624209 18,350 325,000 SH SOLE 325,000 0 0 THERAPEUTICSMD INC COM 88338N107 4,542 775,000 SH SOLE 775,000 0 0 THERAVANCE BIOPHARMA INC COM G8807B106 6,621 602,500 SH SOLE 602,500 0 0 THERMO FISHER SCIENTIFIC INC COM 883556102 12,228 100,000 SH SOLE 100,000 0 0 THORATEC CORP COM NEW 885175307 7,591 120,000 SH SOLE 120,000 0 0 TORNIER N V SHS N87237108 13,457 660,000 SH SOLE 660,000 0 0 PHARMACEUTICAL IN COM 90400D108 10,305 107,000 SH SOLE 107,000 0 0 VALEANT PHARMACEUTICALS INTL COM 91911K102 20,068 112,500 SH SOLE 112,500 0 0 INC COM 92532F100 7,524 72,250 SH SOLE 72,250 0 0 WUXI PHARMATECH CAYMAN INC SPONS ADR SHS 929352102 7,562 175,000 SH SOLE 175,000 0 0 XENOPORT INC COM 98411C100 1,926 555,000 SH SOLE 555,000 0 0 ZS PHARMA INC COM 98979G105 10,177 155,000 SH SOLE 155,000 0 0

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