Tinman Michael Dell is set to buy Quest software for $2.5 billion. The move trumps the bid by Insight Venture Partners and was done on the quiet.

The No. 2 U.S. personal computer maker kept its name out of the limelight when Quest disclosed on Thursday that it had received an offer from a "strategic bidder" of $25.50 per share. Quest's shares rose more than 9 percent to finish at $26.06 on Thursday.

Dell has been actively buying companies to expand its offerings to business and diversify away from personal computers. It told investors its focus on the hardware and software needs of corporate customers was gaining momentum. Quest could help Dell's businesses in data management and protection and Windows server management.

Quest makes software to monitor the flow of data through networks and it has worked with Dell since 2004 and is one of the PC maker's top 10 partners. Dell ranks among Quest's five largest partners.