Executives say they expect the deal to close by the end of the calendar year. Michael's stock was trading in the high $30-range before the deal was announced. The deal takes the retailer private.

The buyers say that they think Michael's is well-positioned for future growth. "We are delighted to partner with the Michael's management team to help build on its already strong position in an attractive industry, and capitalize on the significant growth opportunities that lie ahead," says Matt Levin, a managing director at Bain Capital, in a statement. "We look forward to helping Michael's achieve its full long-term potential."

Bain Capital, based in Boston, has invested in a number of major retailers over the years, bringing them private, including Burlington Coat Factory and Toys "R" Us. New York City-based Blackstone earlier this year acquired office-owner Trizec Properties in a joint venture transaction valued close to $5 billion.

During its most recent completed quarter, which ended on April 29, Michael's same-store sales dropped 3% year over year. Operating income also dropped, 11.4%, to $77.3 million.