Shares of Blackbaud (NASDAQ: BLKB) jumped Monday after the educational software company rejected a buyout offer from Clearlake Capital, which holds an 18.3% stake in it and is its largest shareholder. The stock finished the session up 10.6% on the news. In a press release Monday morning, Blackbaud said that it had received and rejected a takeover proposal from Clearlake Capital that valued the company at $71 a share.