WASHINGTON -- Silicon Graphics Inc. (SGI) Chairman and Chief Executive Robert R. Bishop purchased 100,000 shares of the company's common stock last Thursday, according to a Form 4 released Tuesday by the Securities and Exchange Commission. Bishop bought the shares for $1.34 a share. After the transaction, he directly owned 4.2 million common shares. Shares of the company recently traded at $1.26, down 6 cents or 4.5%.