Control Data to Purchase 20% of Silicon Graphics

Control Data Corp. has agreed to buy about 3 million common shares, or 20%, of Silicon Graphics Inc. for $22.50 a share or a total of about $68.91 million, according to a filing with the Securities and Exchange Commission.

Control Data, which will buy the stock under an agreement dated March 28, plans to complete the deal by the end of April or as soon as the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act expires, Silicon Graphics said in the filing.

As part of its investment in the Mountain View, Calif., producer of computers and graphic systems, Control Data has agreed to buy additional workstations from Silicon Graphics during the next three years. Silicon said the two companies’ business relationship will change in no other way.

The agreement entitles Control Data to nominate one director to Silicon Graphics’ board and stipulates that a third party cannot acquire more than 21% of Silicon Graphics’ voting stock without Control Data’s consent--as long as Control Data owns 10% of the company, according to the filing.