Washington, D.C. 20549

(Name of Issuer)

(Title of Class of Securities)

(CUSIP Number)

(Name, Address and Telephone Number of Person Authorized to
Receive Notices and Communications)

(Date of Event Which Requires Filing of this Statement)

 

 

CUSIP No.		487584 10 4

CUSIP No.		487584 10 4

CUSIP No.		487584 10 4

This Amendment No. 8 to Schedule 13D (this “Amendment No. 8”) relates to the common shares, without par value (the “Common Shares”), of Keithley Instruments, Inc., an Ohio corporation (the “Company”), and is primarily filed to reflect changes to the initial Schedule 13D dated April 12, 1988 (the “Original 13D”), as amended by Amendment No. 1 to Schedule 13D dated February 5, 1990 (“Amendment No. 1”), Amendment No. 2 to Schedule 13D dated March 9, 1991 (“Amendment No. 2”), Amendment No. 3 to Schedule 13D dated November 15, 1997 (“Amendment No. 3”), Amendment No. 4 to Schedule 13D dated February 27, 2004 (“Amendment No. 4”), Amendment No. 5 to Schedule 13D dated March 9, 2009 (“Amendment No. 5”), Amendment No. 6 to Schedule 13D dated March 12, 2009 (“Amendment No. 6”), and Amendment No. 7 to Schedule 13D dated December 8, 2009 (“Amendment No. 7” and, together with Amendment No. 1, Amendment No. 2, Amendment No. 3, Amendment No. 4, Amendment No. 5, and Amendment No. 6, the “Prior Amendments”), as a result of certain amendments to the Amended and Restated Limited Partnership Agreement of the Keithley Investment Co. Limited Partnership (the “Family Partnership”), dated August 1, 1997 (the “Family Partnership Agreement”). Except as otherwise reflected in this Amendment No. 8, there have been no material changes to the information contained in the Original 13D, as amended by the Prior Amendments.

ITEM 5. INTEREST IN SECURITIES OF THE ISSUER

Item 5 of the Schedule 13D is hereby amended as follows:

The following table shows the number and percentage of Common Shares beneficially owned by each of the Investors and by the Investors as a group as of April 9, 2010.

Name		Common Shares				Percent of Class
Family Partnership			1,954,816	(1)			12.41	%
Joseph P. Keithley			2,837,936	(2)			17.40	%
Investors as a group			2,837,936				17.40	%

All holders of Class B Shares are entitled to convert any or all of their Class B Shares into Common Shares at any time on a share-for-share basis. Each Class B Share is entitled to ten votes on all matters presented for a vote to the shareholders of the Company. Accordingly, the Investors are entitled to exercise 62.72% of the voting power on all matters presented for a vote to the shareholders of the Company, including the election of directors.

Except as otherwise described in this Amendment No. 8, the Investors have not engaged in any transactions in the Common Shares or the Class B Shares in the past 60 days.

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ITEM 6. CONTRACTS, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONSHIPS WITH RESPECT TO SECURITIES OF THE ISSUER

Item 6 of the Schedule 13D is hereby amended as follows:

On April 1, 2010, Joseph P. Keithley (the “General Partner”), the Joseph F. Keithley 1988 Family Trust f/b/o Joseph P. Keithley u/a/dtd 4/12/88, the Joseph F. Keithley 1988 Family Trust f/b/o Roy F. Keithley u/a/dtd 4/12/88, and the Joseph F. Keithley 1988 Family Trust f/b/o Elizabeth M. Keithley u/a/dtd 4/12/88 amended the Family Partnership Agreement to extend the term of the Family Partnership until the earlier of December 12, 2018 or the date on which the Family Partnership no longer owns any Common Shares. Prior to the amendment, the term of the Family Partnership continued until December 12, 2013, unless it was earlier dissolved and terminated pursuant to the provisions of the Family Partnership Agreement.

In addition to extending the term of the Family Partnership, the Family Partnership Agreement was amended to clarify and/or modify (i) the definition and succession of the General Partner, (ii) the procedures for dissolution of the Family Partnership and related matters, (iii) the transfer of a partner’s partnership interest, and (iv) certain provisions to correspond to modifications made relating to the 2:1 split of the stock of the Company on June 1, 2000, including a reduction in the minimum per share price with respect to Common Shares that may be sold by the General Partner in the event the dividends generated by the Common Shares are insufficient to make certain required distributions set forth in the amended Family Partnership Agreement.

The Amendment to the Family Partnership Agreement, dated April 1, 2010, is filed as Exhibit 2 hereto and is incorporated herein by reference.

ITEM 7. MATERIAL TO BE FILED AS EXHIBITS

1. Agreement among the Investors to file a joint statement on Schedule 13D.

2. Amendment to the Amended and Restated Limited Partnership Agreement of the Keithley Investment Co. Limited Partnership, dated April 1, 2010.

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SIGNATURES

After reasonable inquiry and to the best of his or its knowledge and belief, each of the undersigned hereby certifies that the information set forth in this statement is true, complete and correct as of April 9, 2010.