13F-HR 1 d341689d13fhr.txt 13F-HR ================================================================================ 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, 2012 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: DIAMONDBACK CAPITAL MANAGEMENT Address: ONE LANDMARK SQUARE STAMFORD, CT 06901 13 File Number: 28-11513 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: Timothy M. Higgins Title: Chief Financial Officer Phone: 203 399 1600 Signature, Place and Date of Signing: Stamford, CT May 15, 2012 Report Type (Check only one.): [X] 13F HOLDINGS REPORT. [ ] 13F NOTICE. [ ] 13F COMBINATION REPORT. I AM SIGNING THIS REPORT AS REQUIRED BY THE SECURITIES EXCHANGE ACT OF 1934 ================================================================================ FORM 13F SUMMARY PAGE Report Summary: Number of Other Included Managers: 0 Form 13F Information Table Entry Total: 583 Form 13F Information Table Value Total: 3802282

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