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 *
KAISER RONALD W
   2. Issuer Name and Ticker or Trading Symbol
OPNET TECHNOLOGIES INC [OPNT] 		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)
C/O OPNET TECHNOLOGIES, INC., 7255 WOODMONT AVENUE		 3. Date of Earliest Transaction (Month/Day/Year)
12/18/2012
(Street)

BETHESDA, MD 20814		 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 12/18/2012   U   40,000 D $ 41.78 (1) 3,000 D  
Common Stock 12/18/2012   D   3,000 D $ 41.78 (2) 0 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

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
KAISER RONALD W
C/O OPNET TECHNOLOGIES, INC.
7255 WOODMONT AVENUE
BETHESDA, MD 20814		   X      

Signatures

 /s/Ronald W. Kaiser   12/20/2012
**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) These shares are being disposed of in connection with a Tender Offer Statement filed by Riverbed Technology, Inc. ("Riverbed") and Octagon Acquisition Corp. ("Octagon") relating to the offer by Octagon to purchase all of the issued and outstanding shares of common stock of the Issuer. The tender price of the shares of common stock is (i) $36.55 in cash; and (ii) 0.2774 of a share of common stock of Riverbed. The purchase price shown is based on the closing price of Riverbed common stock on December 17, 2012 of $18.85 per share.
(2) These shares were disposed of in connection with a merger by and between Riverbed and Octagon pursuant to which the issuer became a wholly-owned subsidiary of Riverbed. As a result of the merger, each outstanding share of common stock was automatically converted into the right to receive: (i) $36.55 in cash; and (ii) 0.2774 shares of Riverbed common stock, without interest thereon and subject to any tax withholding. The price is based on the closing price of Riverbed common stock on December 17, 2012 of $18.85 per share.

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