Business technology maker BMC Software Inc is expected to receive final takeover bids on April 22, with potential buyers pared down to two private equity groups, four people close to the matter said on Thursday.

Shares of BMC rose 1.7 percent to $45.50 on Nasdaq, valuing the Houston, Texas-based company at about $6.5 billion.

Buyout firm Thoma Bravo has joined a bidding group led by KKR & Co LP and TPG Capital LP, while Bain Capital LLC and Golden Gate Capital remain teamed up for the auction, the people added.

The private equity firms are finalizing financing for their respective bids, said the sources, who asked not to be named because the talks are private.

BMC could receive final bids ranging from the mid- to upper $40s per share, one of the sources said.

Buoyant debt markets have encouraged private equity to consider larger deals which in turn call for larger equity checks and make buyout firms more open to teaming up.

In the most striking example this year, Blackstone Group LP, KKR, Carlyle Group LP and Singapore's state investor Temasek Holdings joined forces to submit an $11.1 billion offer for genetic testing equipment maker Life Technologies Corp, people familiar with the matter told Reuters this week.

The private equity firms looking at BMC are coming up against a couple of challenges, including a recent rally in its stock as well as options around the company's two different businesses: mainframe and enterprise service management businesses, one of the sources said.

BMC, which competes with Oracle Corp, SAP AG, CA Inc and Compuware Corp, was under pressure from Paul Singer's activist hedge fund Elliott Management to sell itself last year.