# EDGAR Filing Document

**Accession Number:** 0001009258
**File Stem:** 0001213900-26-057678
**Filing Date:** 2026-5
**Character Count:** 13000
**Document Hash:** 255940193c76512cdfd76d55cfb4d187
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001213900-26-057678.hdr.sgml**: 20260515

**ACCESSION NUMBER**: 0001213900-26-057678

**CONFORMED SUBMISSION TYPE**: 13F-HR

**PUBLIC DOCUMENT COUNT**: 2

**CONFORMED PERIOD OF REPORT**: 20260331

**FILED AS OF DATE**: 20260515

**DATE AS OF CHANGE**: 20260515

**EFFECTIVENESS DATE**: 20260515

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** DEERFIELD MANAGEMENT COMPANY, L.P.
- **CENTRAL INDEX KEY:** 0001009258

**ORGANIZATION NAME:**
- **EIN:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 13F-HR
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 028-05366
- **FILM NUMBER:** 26986590

**BUSINESS ADDRESS:**
- **STREET 1:** 345 PARK AVENUE SOUTH, 12TH FLOOR
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10010
- **BUSINESS PHONE:** 2125511600

**MAIL ADDRESS:**
- **STREET 1:** 345 PARK AVENUE SOUTH, 12TH FLOOR
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10010

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** DEERFIELD MANAGEMENT COMPANY, L.P. (SERIES C)
- **DATE OF NAME CHANGE:** 20180109

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** DEERFIELD MANAGEMENT CO
- **DATE OF NAME CHANGE:** 20131114

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** DEERFIELD MANAGEMENT CO /NY
- **DATE OF NAME CHANGE:** 19981022

### FORM 13F COVER PAGE

**Report for the Calendar Year or Quarter Ended:** 03-31-2026

**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:** DEERFIELD MANAGEMENT COMPANY L.P.<br>**Address:** 345 PARK AVENUE SOUTH 12TH FLOOR<br>NEW YORK, NY 10010

**Form 13F File Number:** 028-05366

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:** Jonathan Isler Deerfield UGP LLC its general partner<br>**Title:** Chief Financial Officer<br>**Phone:** 212-551-1600

**Signature, Place, and Date of Signing:**

/s/ Jonathan Isler  New York, NY  05-15-2026<br>[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 are reported 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:** 1

**Form 13F Information Table Entry Total:** 82

**Form 13F Information Table Value Total:** $8476379716

      (round to nearest dollar)

**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.   | Name              | Form 13F File Number   |
|:---|:---|:---|
|  | Deerfield UGP LLC | 028-25875              |

### FORM 13F INFORMATION TABLE

---

|  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| NAME OF ISSUER | TITLE OF CLASS | CUSIP | FIGI | VALUE (x$1000) | SHRS OR PRN AMT | SH/PRN | PUT/CALL | INVESTMENT DISCRETION | OTHER MANAGER | VOTING AUTHORITY | VOTING AUTHORITY | VOTING AUTHORITY |
| NAME OF ISSUER | TITLE OF CLASS | CUSIP | FIGI | VALUE (x$1000) | SHRS OR PRN AMT | SH/PRN | PUT/CALL | INVESTMENT DISCRETION | OTHER MANAGER | SOLE | SHARED | NONE |
| ACADIA HEALTHCARE COMPANY IN | COM | 00404A109 |  | 105722800 | 4520000 | SH |  | DFND | 1 | 4520000 | 0 | 0 |
| ADAPTHEALTH CORP | COMMON STOCK | 00653Q102 |  | 136584987 | 11477730 | SH |  | DFND | 1 | 11477730 | 0 | 0 |
| ALECTOR INC | COM | 014442107 |  | 2268663 | 1055192 | SH |  | DFND | 1 | 1055192 | 0 | 0 |
| ALIGNMENT HEALTHCARE INC | NOTE   4.250%11/1 | 01625VAB0 |  | 85858720 | 61000000 | PRN |  | DFND | 1 | 61000000 | 0 | 0 |
| ALNYLAM PHARMACEUTICALS INC | COM | 02043Q107 |  | 22477653 | 67935 | SH |  | DFND | 1 | 67935 | 0 | 0 |
| ANNEXON INC | COM | 03589W102 |  | 3234878 | 583913 | SH |  | DFND | 1 | 583913 | 0 | 0 |
| ARROWHEAD PHARMACEUTICALS IN | COM | 04280A100 |  | 98645722 | 1573297 | SH |  | DFND | 1 | 1573297 | 0 | 0 |
| ARROWHEAD PHARMACEUTICALS IN | NOTE           1/1 | 04280AAC4 |  | 207181800 | 200000000 | PRN |  | DFND | 1 | 200000000 | 0 | 0 |
| ARS PHARMACEUTICALS INC | COM | 82835W108 |  | 60255610 | 7503812 | SH |  | DFND | 1 | 7503812 | 0 | 0 |
| BELITE BIO INC | SPONSORED ADS | 07782B104 |  | 48471833 | 304013 | SH |  | DFND | 1 | 304013 | 0 | 0 |
| BETA BIONICS INC | COM | 08659B102 |  | 13266480 | 1324000 | SH |  | DFND | 1 | 1324000 | 0 | 0 |
| BIO RAD LABS INC | CL A | 090572207 |  | 63017013 | 226070 | SH |  | DFND | 1 | 226070 | 0 | 0 |
| BIOCRYST PHARMACEUTICALS INC | COM | 09058V103 |  | 143161760 | 15038000 | SH |  | DFND | 1 | 15038000 | 0 | 0 |
| BIOMARIN PHARMACEUTICAL INC | COM | 09061G101 |  | 48104398 | 851556 | SH |  | DFND | 1 | 851556 | 0 | 0 |
| BIOMX INC | COM NEW | 09090D509 |  | 492795 | 131272 | SH |  | DFND | 1 | 131272 | 0 | 0 |
| BRIDGEBIO ONCOLOGY THERAPEUT | COM NEW | 107924102 |  | 43724742 | 4885446 | SH |  | DFND | 1 | 4885446 | 0 | 0 |
| BRIGHT MINDS BIOSCIENCES INC | COM NEW | 10919W405 |  | 20650510 | 283000 | SH |  | DFND | 1 | 283000 | 0 | 0 |
| BROOKDALE SR LIVING INC | COM | 112463104 |  | 159194598 | 11637032 | SH |  | DFND | 1 | 11637032 | 0 | 0 |
| BROOKDALE SR LIVING INC | NOTE   3.500%10/1 | 112463AF1 |  | 505441129 | 306885000 | PRN |  | DFND | 1 | 306885000 | 0 | 0 |
| CAREDX INC | COM | 14167L103 |  | 38035760 | 2191000 | SH |  | DFND | 1 | 2191000 | 0 | 0 |
| CATALYST PHARMACEUTICALS INC | COM | 14888U101 |  | 97643536 | 3943600 | SH |  | DFND | 1 | 3943600 | 0 | 0 |
| CELCUITY INC | COM | 15102K100 |  | 195635960 | 1714000 | SH |  | DFND | 1 | 1714000 | 0 | 0 |
| CENTENE CORP DEL | COM | 15135B101 |  | 193725559 | 5917091 | SH |  | DFND | 1 | 5917091 | 0 | 0 |
| CERTARA INC | COM | 15687V109 |  | 44509049 | 7808605 | SH |  | DFND | 1 | 7808605 | 0 | 0 |
| COGENT BIOSCIENCES INC | COM | 19240Q201 |  | 348099826 | 9043903 | SH |  | DFND | 1 | 9043903 | 0 | 0 |
| COMPASS THERAPEUTICS INC | COM | 20454B104 |  | 19075740 | 3606000 | SH |  | DFND | 1 | 3606000 | 0 | 0 |
| CULLINAN THERAPEUTICS INC | COM | 230031106 |  | 5487461 | 386169 | SH |  | DFND | 1 | 386169 | 0 | 0 |
| DAY ONE BIOPHARMACEUTICALS I | COM | 23954D109 |  | 79823929 | 3723131 | SH |  | DFND | 1 | 3723131 | 0 | 0 |
| DIANTHUS THERAPEUTICS INC | COM | 252828108 |  | 85582707 | 1019813 | SH |  | DFND | 1 | 1019813 | 0 | 0 |
| DISC MEDICINE INC | COM | 254604101 |  | 42008580 | 657000 | SH |  | DFND | 1 | 657000 | 0 | 0 |
| EDWARDS LIFESCIENCES CORP | COM | 28176E108 |  | 1097256 | 13702 | SH |  | DFND | 1 | 13702 | 0 | 0 |
| EMBECTA CORP | COMMON STOCK | 29082K105 |  | 22409055 | 2534961 | SH |  | DFND | 1 | 2534961 | 0 | 0 |
| ENHABIT INC | COM | 29332G102 |  | 66895741 | 4747746 | SH |  | DFND | 1 | 4747746 | 0 | 0 |
| ENVISTA HOLDINGS CORPORATION | COM | 29415F104 |  | 56070237 | 2210100 | SH |  | DFND | 1 | 2210100 | 0 | 0 |
| FOGHORN THERAPEUTICS INC | COM | 344174107 |  | 21005074 | 4394367 | SH |  | DFND | 1 | 4394367 | 0 | 0 |
| GENMAB A/S | SPONSORED ADS | 372303206 |  | 66055460 | 2462000 | SH |  | DFND | 1 | 2462000 | 0 | 0 |
| HUMANA INC | COM | 444859102 |  | 158999 | 917 | SH |  | DFND | 1 | 917 | 0 | 0 |
| IDEAYA BIOSCIENCES INC | COM | 45166A102 |  | 50979867 | 1530008 | SH |  | DFND | 1 | 1530008 | 0 | 0 |
| IMMUNOCORE HLDGS PLC | NOTE   2.500% 2/0 | 45258DAB1 |  | 27025200 | 30000000 | PRN |  | DFND | 1 | 30000000 | 0 | 0 |
| INDIVIOR PHARMACEUTICALS INC | COM | 45579U109 |  | 94420639 | 3097790 | SH |  | DFND | 1 | 3097790 | 0 | 0 |
| INSPIRE MED SYS INC | COM | 457730109 |  | 139433016 | 2703238 | SH |  | DFND | 1 | 2703238 | 0 | 0 |
| IONIS PHARMACEUTICALS INC | NOTE   1.750% 6/1 | 462222AF7 |  | 90613860 | 60000000 | PRN |  | DFND | 1 | 60000000 | 0 | 0 |
| IONIS PHARMACEUTICALS INC | COM | 462222100 |  | 148653345 | 1979669 | SH |  | DFND | 1 | 1979669 | 0 | 0 |
| KYMERA THERAPEUTICS INC | COM | 501575104 |  | 46739849 | 561170 | SH |  | DFND | 1 | 561170 | 0 | 0 |
| KYVERNA THERAPEUTICS INC | COM | 501976104 |  | 17260000 | 2000000 | SH |  | DFND | 1 | 2000000 | 0 | 0 |
| LANTHEUS HLDGS INC | COM | 516544103 |  | 62803724 | 827999 | SH |  | DFND | 1 | 827999 | 0 | 0 |
| LARIMAR THERAPEUTICS INC | COM | 517125100 |  | 160231383 | 35606974 | SH |  | DFND | 1 | 35606974 | 0 | 0 |
| LEGEND BIOTECH CORP | SPONSORED ADS | 52490G102 |  | 139069371 | 7687638 | SH |  | DFND | 1 | 7687638 | 0 | 0 |
| LIVANOVA PLC | NOTE   2.500% 3/1 | 53802LAB8 |  | 40033281 | 34280000 | PRN |  | DFND | 1 | 34280000 | 0 | 0 |
| MIRUM PHARMACEUTICALS INC | NOTE   4.000% 5/0 | 604749AB7 |  | 209440280 | 70000000 | PRN |  | DFND | 1 | 70000000 | 0 | 0 |
| MONOPAR THERAPEUTICS INC | COM NEW | 61023L207 |  | 17737989 | 323745 | SH |  | DFND | 1 | 323745 | 0 | 0 |
| MYRIAD GENETICS INC | COM | 62855J104 |  | 2273 | 505 | SH |  | DFND | 1 | 505 | 0 | 0 |
| NEOGENOMICS INC | NOTE   0.250% 1/1 | 64049MAB6 |  | 66653778 | 72689000 | PRN |  | DFND | 1 | 72689000 | 0 | 0 |
| NEUROCRINE BIOSCIENCES INC | COM | 64125C109 |  | 80361400 | 610000 | SH |  | DFND | 1 | 610000 | 0 | 0 |
| NEWAMSTERDAM PHARMA COMPANY | ORDINARY SHARES | N62509109 |  | 136515896 | 4264789 | SH |  | DFND | 1 | 4264789 | 0 | 0 |
| NEWAMSTERDAM PHARMA COMPANY | *W EXP 99/99/999 | N62509117 |  | 1859451 | 92787 | SH |  | DFND | 1 | 92787 | 0 | 0 |
| NUVALENT INC | COM | 670703107 |  | 1767103703 | 17248450 | SH |  | DFND | 1 | 17248450 | 0 | 0 |
| PFIZER INC | COM | 717081103 |  | 85363200 | 3040000 | SH |  | DFND | 1 | 3040000 | 0 | 0 |
| PHARVARIS N V | COM | N69605108 |  | 88310687 | 3126042 | SH |  | DFND | 1 | 3126042 | 0 | 0 |
| PMV PHARMACEUTICALS INC | COM | 69353Y103 |  | 10900 | 8790 | SH |  | DFND | 1 | 8790 | 0 | 0 |
| PRAXIS PRECISION MEDICINES I | COM NEW | 74006W207 |  | 310382059 | 963351 | SH |  | DFND | 1 | 963351 | 0 | 0 |
| QUANTUM SI INC | *W EXP 06/10/202 | 74765K113 |  | 36200 | 333333 | SH |  | DFND | 1 | 333333 | 0 | 0 |
| REVOLUTION MEDICINES INC | COM | 76155X100 |  | 223383250 | 2297000 | SH |  | DFND | 1 | 2297000 | 0 | 0 |
| SAVARA INC | COM | 805111101 |  | 74086740 | 13569000 | SH |  | DFND | 1 | 13569000 | 0 | 0 |
| SIONNA THERAPEUTICS INC | COM | 829401108 |  | 38910953 | 970590 | SH |  | DFND | 1 | 970590 | 0 | 0 |
| SPYGLASS PHARMA INC | COM SHS | 85220G109 |  | 14250500 | 550000 | SH |  | DFND | 1 | 550000 | 0 | 0 |
| STOKE THERAPEUTICS INC | COM | 86150R107 |  | 59373160 | 1823500 | SH |  | DFND | 1 | 1823500 | 0 | 0 |
| STRUCTURE THERAPEUTICS INC | SPONSORED ADS | 86366E106 |  | 37017263 | 767993 | SH |  | DFND | 1 | 767993 | 0 | 0 |
| SURROZEN INC | *W EXP 08/01/203 | 86889P117 |  | 2667 | 166666 | SH |  | DFND | 1 | 166666 | 0 | 0 |
| SYNDAX PHARMACEUTICALS INC | COM | 87164F105 |  | 88298464 | 3779900 | SH |  | DFND | 1 | 3779900 | 0 | 0 |
| TANGO THERAPEUTICS INC | COM | 87583X109 |  | 86751328 | 4146813 | SH |  | DFND | 1 | 4146813 | 0 | 0 |
| TAYSHA GENE THERAPIES INC | COM SHS | 877619106 |  | 12168078 | 2722165 | SH |  | DFND | 1 | 2722165 | 0 | 0 |
| THE ONCOLOGY INSTITUTE INC | *W EXP 99/99/999 | 68236X118 |  | 54750 | 1250000 | SH |  | DFND | 1 | 1250000 | 0 | 0 |
| THE ONCOLOGY INSTITUTE INC | COM | 68236X100 |  | 10315360 | 3360052 | SH |  | DFND | 1 | 3360052 | 0 | 0 |
| TYRA BIOSCIENCES INC | COM | 90240B106 |  | 21026700 | 549000 | SH |  | DFND | 1 | 549000 | 0 | 0 |
| UNITED THERAPEUTICS CORP DEL | COM | 91307C102 |  | 270991860 | 457000 | SH |  | DFND | 1 | 457000 | 0 | 0 |
| VERA THERAPEUTICS INC | CL A | 92337R101 |  | 149740083 | 3722100 | SH |  | DFND | 1 | 3722100 | 0 | 0 |
| VERACYTE INC | COM | 92337F107 |  | 23384460 | 726000 | SH |  | DFND | 1 | 726000 | 0 | 0 |
| VERADERMICS INC | COMMON STOCK | 922967104 |  | 315750 | 5000 | SH |  | DFND | 1 | 5000 | 0 | 0 |
| VIATRIS INC | COM | 92556V106 |  | 272985357 | 20206170 | SH |  | DFND | 1 | 20206170 | 0 | 0 |
| XENON PHARMACEUTICALS INC | COM | 98420N105 |  | 93952722 | 1615696 | SH |  | DFND | 1 | 1615696 | 0 | 0 |
| ZENAS BIOPHARMA INC | NOTE   2.500% 4/0 | 98937LAA3 |  | 67252900 | 65000000 | PRN |  | DFND | 1 | 65000000 | 0 | 0 |

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