Keithley Instruments, Inc. (NYSE:KEI), a world leader in advanced electrical test instruments and systems, today announced that it joined the broad-market Russell 3000® Index when Russell Investments reconstituted its comprehensive set of U.S. and global equity indexes on June 25, 2010 after the close of the U.S. markets. Russell Investments posted the final membership lists today.

Annual reconstitution of Russell's U.S. indexes captures the 4,000 largest U.S. stocks as of the end of May, ranking them by total market capitalization. Membership in the Russell 3000, which remains in place for one year, means automatic inclusion in the large-cap Russell 1000® Index or small-cap Russell 2000® Index as well as the appropriate growth and value style indexes. The Russell 3000 also serves as the U.S. component to the Russell Global Index. Russell determines membership for its equity indexes primarily by objective, market-capitalization rankings and style attributes.

The Company's Chairman, President, and Chief Executive Officer, Joseph P. Keithley stated, ?We are pleased to be added to the Russell 3000® Index and we anticipate that our inclusion in this index will increase awareness of Keithley among institutional investors and the investment community in general. Our strategy is to focus on our core test and measurement business. The sustainable improvements that we have made in our cost structure provide excellent operating leverage opportunities with our new business model.?

Russell indexes are widely used by investment managers and institutional investors for index funds and as benchmarks for both passive and active investment strategies. An industry-leading $3.9 trillion in assets currently are benchmarked to them. Russell's investment tools originated from Russell's multi-manager investment business in the early 1980s when the company saw the need for a more objective, market-driven set of benchmarks in order to evaluate outside investment managers.

Total returns data for the Russell 3000 and other Russell Indexes is available at http://www.russell.com/Indexes/performance/default.asp.

About Russell Investments

Russell Investments provides strategic advice, world-class implementation, state-of-the-art performance benchmarks and a range of institutional-quality investment products. Russell has $179 billion in assets under management as of March 31, 2010, and serves individual, institutional and advisor clients in more than 40 countries. Founded in 1936, Russell is a subsidiary of The Northwestern Mutual Life Insurance Company.

About Keithley Instruments, Inc.

With more than 60 years of measurement expertise, Keithley Instruments has become a world leader in advanced electrical test instruments and systems. Our customers are scientists and engineers in the worldwide electronics industry involved with advanced materials research, semiconductor device development and fabrication, and the production of end products such as portable wireless devices. The value we provide them is a combination of products for their critical measurement needs and a rich understanding of their applications to improve the quality of their products and reduce their cost of test.

Forward-Looking Statements

Statements in this release that are not historical facts, including those relating to sustainable improvements to the Company's cost structure are ?forward-looking statements,? as defined in the Private Securities Litigation Reform Act of 1995, that involve a number of risks and uncertainties. Actual results may differ materially from the results stated or implied in the forward-looking statements as a result of a number of factors that include, but are not limited to: worldwide economic conditions; uncertainties in the credit and capital markets; business conditions in the semiconductor, wireless, precision electronics and other segments of the worldwide electronics industry; the ability of the Company to effectively sell to its customers as a result of a reduction in force and a refocus of the Company's field sales organization; the Company's ability to implement and realize the benefits of planned cost savings without adversely affecting the Company's product development programs and strategic initiatives; the timing of large orders from customers or canceling orders in backlog; changes in product and sales mix, and the related effects on gross margins; the Company's ability to develop new products in a timely fashion and gain market acceptance of those products to remain competitive and gain market share; the Company's ability to work with third parties; competitive factors, including pricing pressures, loss of key employees, technological developments and new products offered by competitors; and the impact of the Company's fixed costs in a period of stabilizing sales. Further information on factors that could cause actual results to differ from those anticipated is included in the Company's annual report on Form 10-K and quarterly reports on Form 10-Q which are filed with the Securities and Exchange Commission. In light of these uncertainties, the inclusion of forward-looking information should not be regarded as a representation by the Company that its plans or objectives will be achieved. Further, the Company is not obligating itself to revise forward-looking statements contained herein to reflect events or circumstances after the date of this release or to reflect the occurrence of unanticipated events.

Keithley Instruments, Inc.
Mark J. Plush, 440-248-0400
Senior Vice President and Chief Financial Officer
Fax: 440-248-6168
http://www.keithley.com