Ownership Submission
FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
Morse Timothy R.
  2. Issuer Name and Ticker or Trading Symbol
F5 NETWORKS INC [FFIV]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director _____ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
(Last)
(First)
(Middle)
401 ELLIOTT AVENUE WEST
3. Date of Earliest Transaction (Month/Day/Year)
03/14/2012
(Street)

SEATTLE, WA 98119
4. If Amendment, Date Original Filed(Month/Day/Year)
6. Individual or Joint/Group Filing(Check Applicable Line)
_X_ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)
2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code
(Instr. 8)
4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)
5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)
6. Ownership Form: Direct (D) or Indirect (I)
(Instr. 4)
7. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V Amount (A) or (D) Price
Common Stock 03/14/2012   M   1,836 (1) A $ 0 26,530 D  

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 3)
2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction Code
(Instr. 8)
5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4, and 5)
6. Date Exercisable and Expiration Date
(Month/Day/Year)
7. Title and Amount of Underlying Securities
(Instr. 3 and 4)
8. Price of Derivative Security
(Instr. 5)
9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 4)
10. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 4)
11. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
Restricted Stock Units (2) $ 0 03/14/2012   M     1,836 03/14/2012   (3) Common Stock 1,836 $ 0 0 D  
Restricted Stock Units (2) $ 0 03/15/2012   A   1,512     (4)   (4) Common Stock 1,512 $ 0 1,512 D  

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
Morse Timothy R.
401 ELLIOTT AVENUE WEST
SEATTLE, WA 98119
  X      

Signatures

 /s/ Jeffrey A. Christianson by Power of Attorney   03/16/2012
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) Shares received upon vesting of the March 14, 2011 grant of Restricted Stock Units.
(2) Each Restricted Stock Unit represents a contingent right to receive one share of Common Stock of F5 Networks, Inc. on the vest date.
(3) One share of Common Stock of F5 Networks, Inc. was delivered to the reporting person for each Restricted Stock Unit that vested on March 14, 2012.
(4) Restricted Stock Units will fully vest on the first business day prior to the date of the annual shareholder meeting for fiscal 2012 (to be held in 2013) if the reporting person continues to serve as a director on the vest date, and the corresponding number of shares of Common Stock of F5 Networks, Inc. will be issued to the reporting person on the vest date.

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