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* HOERSTEN MARK A (Last) (First) (Middle) KEITHLEY INSTRUMENTS, INC. 28775 AURORA ROAD (Street) SOLON OH 44139 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol KEITHLEY INSTRUMENTS INC [ KEI ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director 10% Owner X Officer (give title below) Other (specify below) VP Business Management
	3. Date of Earliest Transaction (Month/Day/Year) 12/08/2010
	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 Shares	12/08/2010		D(1)		10,135	D	$21.6	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
Common Share Option	$18.41	12/08/2010		D(2)			25,000	07/25/2003(3)	07/24/2011	Common Shares	25,000	$3.19	0	D
Common Share Option	$13.76	12/08/2010		D(4)			30,000	07/24/2004(3)	07/23/2012	Common Shares	30,000	$7.84	0	D
Common Share Option	$16.12	12/08/2010		D(5)			30,000	08/10/2005(6)	07/18/2013	Common Shares	30,000	$5.48	0	D
Common Share Option	$18.75	12/08/2010		D(7)			25,000	02/15/2005(8)	07/16/2014	Common Shares	25,000	$2.85	0	D
Common Share Option	$15.05	12/08/2010		D(9)			8,800	10/04/2007(3)	10/03/2015	Common Shares	8,800	$6.55	0	D
Common Share Option	$14	12/08/2010		D(10)			8,800	01/30/2009(3)	01/30/2017	Common Shares	8,800	$7.6	0	D
Common Share Option	$9.12	12/08/2010		D(11)			7,500	11/09/2009(3)	11/09/2017	Common Shares	7,500	$12.48	0	D
Common Stock Option	$2.99	12/08/2010		D(12)			16,400	02/06/2011(3)	02/06/2019	Common Shares	16,400	$18.61	0	D
Restricted Unit Award	$0.00	12/08/2010		D(13)			5,500	(14)	(14)	Common Shares	5,500	$21.6	0	D
Common Share Option	$4.26	12/08/2010		D(15)			13,200	12/04/2011(16)	12/04/2019	Common Shares	13,200	$17.34	0	D
Performance Award Unit	$0.00	12/08/2010		D(13)			6,600	09/30/2012(17)	(17)	Common Shares	6,600	$21.6	0	D
Restricted Unit Award	$0.00	12/08/2010		D(13)			4,400	(18)	(18)	Common Shares	4,400	$21.6	0	D

Explanation of Responses:

1. Disposed of pursuant to an Agreement and Plan of Merger, dated as of September 29, 2010 (the "Merger Agreement") by and among Danaher Corporation, Aegean Acquisition Corp. and the Issuer in exchange for the merger consideration of $21.60 in cash per share.

2. The options were cancelled pursuant to the Merger Agreement in exchange for the merger consideration of $21.60 in cash per share, less the exercise price per share of $18.41.

3. Date reported applied to 50% of total, one-half of the balance was then exercisable in each succeeding year.

4. The options were cancelled pursuant to the Merger Agreement in exchange for the merger consideration of $21.60 in cash per share, less the exercise price per share of $13.76.

5. The options were cancelled pursuant to the Merger Agreement in exchange for the merger consideration of $21.60 in cash per share, less the exercise price per share of $16.12.

6. Option became fully vested on August 10, 2005

7. The options were cancelled pursuant to the Merger Agreement in exchange for the merger consideration of $21.60 in cash per share, less the exercise price of $18.75.

8. Option became fully vested on February 15, 2005

9. The options were cancelled pursuant to the Merger Agreement in exchange for the merger consideration of $21.60 in cash per share, less the exercise price per share of $15.05.

10. The options were cancelled pursuant to the Merger Agreement in exchange for the merger consideration of $21.60 in cash per share, less the exercise price per share of $14.00.

11. The options were cancelled pursuant to the Merger Agreement in exchange for the merger consideration of $21.60 in cash per share, less the exercise price per share of $9.12.

12. The options were cancelled pursuant to the Merger Agreement in exchange for the merger consideration of $21.60 in cash per share, less the exercise price per share of $2.99.

13. The units were cancelled pursuant to the Merger Agreement in exchange for the merger consideration of $21.60 in cash per share.

14. Restricted unit awards were to become fully vested on February 6, 2013. Common shares represented by such vested restricted unit awards were to be delivered promptly after such vesting date.

15. The options were cancelled pursuant to the Merger Agreement in exchange for the merger consideration of $21.60 in cash per share, less the exercise price per share of $4.26.

16. Date applies to 50% of total, remaining balance is exercisable the following year on anniversary date

17. Each Performance Award Unit represented a right to receive one common share. The number of units comprising the initial award were to be adjusted (ranging from a maximum of twice the number of units comprising the initial award, to a minimum of no units), based on award program metrics that compare the Company's total shareholder return performance occurring during the Measurement Period to comparable total shareholder return performance reported by companies in the Russell Microcap Index. Awarded units earned based on these metrics as of September 30, 2012 (the vesting date) were to be converted to shares under the Plan and will be issued on or before December 31, 2012.

18. Restricted unit awards were to become fully vested on December 4, 2013. Common Shares represented by such vested restricted unit awards were to be delivered promptly after such vesting date.

Remarks:

	Mark J. Plush, Attorney-in Fact	12/10/2010
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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