SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
X	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* Reilly Thomas (Last) (First) (Middle) C/O ARCSIGHT, INC. 5 RESULTS WAY (Street) CUPERTINO CA 95014 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol ArcSight Inc [ ARST ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X Director 10% Owner X Officer (give title below) Other (specify below) President and CEO
	3. Date of Earliest Transaction (Month/Day/Year) 10/21/2010
	4. If Amendment, Date of 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

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	10/21/2010		U(1)		6,795	D	$43.5	0	D
Common Stock	10/21/2010		M		14,092(2)	A	$6.8	14,092	D
Common Stock	10/22/2010		D(3)		14,092	D	$43.5	0	D

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 Securities Underlying Derivative Security (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: 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
Stock Option (Right to Buy)	$6.8	10/22/2010		D			14,705	(2)(4)	01/23/2017	Common Stock	14,705	(2)	0	D
Stock Option (Right to Buy)	$6.8	10/22/2010		D			775,575	(4)	01/23/2017	Common Stock	775,575	(5)	0	D
Stock Option (Right to Buy)	$6.8	10/22/2010		D			290,484	(4)	01/23/2017	Common Stock	290,484	(6)	0	D
Stock Option (Right to Buy)	$8.5	10/22/2010		D			46,313	(7)	06/17/2018	Common Stock	46,313	(8)	0	D
Stock Option (Right to Buy)	$7.76	10/22/2010		D			200,000	(9)	09/30/2018	Common Stock	200,000	(10)	0	D
Stock Option (Right to Buy)	$7.76	10/22/2010		D			200,000	(11)	09/30/2018	Common Stock	200,000	(12)	0	D
Stock Option (Right to Buy)	$18	10/22/2010		D			125,000	(13)	06/08/2019	Common Stock	125,000	(14)	0	D
Stock Option (Right to Buy)	$21.63	10/22/2010		D			131,500	(15)	05/18/2020	Common Stock	131,500	(16)	0	D

Explanation of Responses:

1. Pursuant to the terms of the tender offer by Priam Acquisition Corporation, a Delaware corporation ("Purchaser") and a wholly-owned, direct or indirect, subsidiary of Hewlett-Packard Company, a Delaware corporation ("HP"), to purchase all outstanding shares of Issuer Common Stock, disclosed in the Tender Offer Statement on Schedule TO filed with the Securities and Exchange Commission (the "Tender Offer"), Purchaser accepted for payment of $43.50 per share all shares validly tendered on or prior to October 20, 2010.

2. 14,092 shares under this option were exercised pursuant to a conditional exercise program effective on the satisfaction of the closing conditions to the merger (the "Merger") contemplated by that certain Agreement and Plan of Merger by and among the Issuer, HP and Purchaser, dated as of September 13, 2010 (the "Merger Agreement"), and such shares were converted into the right to receive $43.50 per share and the remaining shares under the option were assumed and exchanged for an option to purchase 622 shares of HP Common Stock at an exercise price per share of $6.70.

3. All shares issued and outstanding immediately prior to the effectiveness of the Merger and not tendered in the Tender Offer were converted into the right to receive $43.50 in cash per share.

4. The option vests and becomes exercisable as to 1/4th of the shares on November 27, 2007 and vests and becomes exercisable as to 1/48th of the shares at the end of each full month thereafter.

5. Pursuant to the terms of the Merger, 739,877 shares under this option were cancelled in exchange for a cash payment to the Reporting Person equal to the difference between the offer price per share of $43.50 and the exercise price per share of the option and the remaining shares under the option were assumed and exchanged for an option to purchase 36,247 shares of HP Common Stock at an exercise price per share of $6.70.

6. Pursuant to the terms of the Merger, 278,380 shares under this option were cancelled in exchange for a cash payment to the Reporting Person equal to the difference between the offer price per share of $43.50 and the exercise price per share of the option and the remaining shares under the option were assumed and exchanged for an option to purchase 12,290 shares of HP Common Stock at an exercise price per share of $6.70.

7. The option vests and becomes exercisable as to 1/4th of the shares on May 1, 2009 and vests and becomes exercisable as to 1/48th of the shares at the end of each full month thereafter.

8. Pursuant to the terms of the Merger, 27,980 shares under this option were cancelled in exchange for a cash payment to the Reporting Person equal to the difference between the offer price per share of $43.50 and the exercise price per share of the option and the remaining shares under the option were assumed and exchanged for an option to purchase 18,615 shares of HP Common Stock at an exercise price per share of $8.38.

9. The option vests and becomes exercisable as 1/72nd of the shares at the end of each full month after October 1, 2008.

10. Pursuant to the terms of the Merger, 66,666 shares under this option were cancelled in exchange for a cash payment to the Reporting Person equal to the difference between the offer price per share of $43.50 and the exercise price per share of the option and the remaining shares under the option were assumed and exchanged for an option to purchase 135,388 shares of HP Common Stock at an exercise price per share of $7.65.

11. The option vests and becomes exercisable as to 1/4th of the shares on October 1, 2009 and vests and becomes exercisable as to 1/48th of the shares at the end of each full month thereafter.

12. Pursuant to the terms of the Merger, 100,000 shares under this option were cancelled in exchange for a cash payment to the Reporting Person equal to the difference between the offer price per share of $43.50 and the exercise price per share of the option and the remaining shares under the option were assumed and exchanged for an option to purchase 101,540 shares of HP Common Stock at an exercise price per share of $7.65.

13. The option vests and becomes exercisable as to 1/4th of the shares on May 1, 2010 and vests and becomes exercisable as to 1/48th of the shares at the end of each full month thereafter.

14. Pursuant to the terms of the Merger, 44,270 shares under this option were cancelled in exchange for a cash payment to the Reporting Person equal to the difference between the offer price per share of $43.50 and the exercise price per share of the option and the remaining shares under the option were assumed and exchanged for an option to purchase 81,973 shares of HP Common Stock at an exercise price per share of $17.73.

15. The option vests and becomes exercisable as to 1/4th of the shares on May 1, 2011 and vests and becomes exercisable as to 1/48th of the shares at the end of each full month thereafter.

16. Pursuant to the terms of the Merger, this option was assumed and exchanged for an option to purchase 133,525 shares of HP Common Stock at an exercise price per share of $21.31.

Remarks:

	/s/ Tram T. Phi as attorney-in-fact for Thomas Reilly	10/25/2010
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* 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).
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