0000950123-11-050378.txt : 20110516 0000950123-11-050378.hdr.sgml : 20110516 20110516060108 ACCESSION NUMBER: 0000950123-11-050378 CONFORMED SUBMISSION TYPE: 13F-HR/A PUBLIC DOCUMENT COUNT: 1 CONFORMED PERIOD OF REPORT: 20100331 FILED AS OF DATE: 20110516 DATE AS OF CHANGE: 20110516 EFFECTIVENESS DATE: 20110516 FILER: COMPANY DATA: COMPANY CONFORMED NAME: Magnetar Financial LLC CENTRAL INDEX KEY: 0001352851 IRS NUMBER: 043818748 STATE OF INCORPORATION: DE FISCAL YEAR END: 1231 FILING VALUES: FORM TYPE: 13F-HR/A SEC ACT: 1934 Act SEC FILE NUMBER: 028-11800 FILM NUMBER: 11843253 BUSINESS ADDRESS: STREET 1: 1603 ORRINGTON AVE. STREET 2: 13TH FLOOR CITY: EVANSTON STATE: IL ZIP: 60201 BUSINESS PHONE: (847)905-4400 MAIL ADDRESS: STREET 1: 1603 ORRINGTON AVE. STREET 2: 13TH FLOOR CITY: EVANSTON STATE: IL ZIP: 60201 13F-HR/A 1 c17348e13fvhrza.txt 13F HOLDINGS REPORT AMENDMENT UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 13F Form 13F COVER PAGE Report for the Calendar Year or Quarter Ended: March 31, 2010 Check here if Amendment [X]; Amendment Number: 4 This Amendment (Check only one.): [ ] is a restatement. [X] adds new holdings entries. Institutional Investment Manager Filing this Report: Name: Magnetar Financial LLC Address: 1603 Orrington Avenue, 13th Floor Evanston, IL 60201 Form 13F File Number: 28-11800 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: Michael Turro Title: Chief Compliance Officer Phone: 847-905-4690 Signature, Place, and Date of Signing: /s/ Michael Turro Evanston, IL May 16, 2011 ------------------------------------- ------------- ------------ [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: 0 Form 13F Information Table Entry Total: 1 Form 13F Information Table Value Total: $24,694 (thousands) List of Other Included Managers: NONE FORM 13F INFORMATION TABLE

COLUMN 1 COLUMN 2 COLUMN 3 COLUMN 4 COLUMN 5 COLUMN 6 COLUMN 7 COLUMN 8 ---------- -------- --------- -------- ---------------- ---------- -------- ------------------- VOTING AUTHORITY NAME OF TITLE OF VALUE SHRS OR SH/ PUT/ INVESTMENT OTHER ------------------- ISSUER CLASS CUSIP [x$1000] PRN AMT PRN CALL DISCRETION MANAGERS SOLE SHARED NONE ---------- -------- --------- -------- ------- --- ---- ---------- -------- ------- ------ ---- AIRGAS INC COM 009363102 24,694 388,142 SH SOLE 388,142