Diane Rehm had Eileen Appelbaum, Megan McArdle, and Steve Kaplan on her show debating the merits of private equity firms. Springboarding off the animosity toward private equity firms due in part to Newt Gingrich's criticisms of Bain Capital and Mitt Romney, Ms. Appelbaum, on two occasions, brings up Mervyn's, a clothing retailer that was taken into bankruptcy by the private equity firms that purchased the company from its founder a few years earlier.
The private equity firms (there were more than one) that purchased Mervyn's split the company into two separate entities, creating a commercial property company and a clothing retailer. Apparently Mervyn's owned the real estate on which its stores operated. After setting up the commercial property entity, the company soon discovered that rents for the property currently occupied by Mervyn's stores increased substantially, which means Mervyn's had been operating with an accounting profit, but after taking into account the opportunity cost of its real estate holdings, not an economic profit.
Mervyn's had already been struggling as a retailer in an increasingly competitive market. The company also failed to change its image, effectively failing to find and serve a niche market, which caused it to lose revenue. Once the company was split in two, Mervyn's had to pay the opportunity cost of using its properties, causing them to operate at a loss. They were a losing venture prior to being bought by the private equity firms, and these firms only exposed inefficiency of the operation.
The example of Mervyn's is a virtue of private equity firms, not the villainous rogues Appelbaum makes them out to be. Something similar happened to the large department store Woodward & Lothrop. That company was bought out by Alfred Taubman, who subsequently liquidated the company after finding it losing market share in a more competitive market. The effect of Taubman purchasing Woodward & Lothrop and then taking into Chapter 7 liquidation was a benefit to the store's creditors, including its employees, both current and retired. Without Taubman taking the company into bankruptcy when he did, it likely would have depleted the capital it had, leaving these employees and retirees with a lot less. By taking it into bankruptcy and liquidating its assets, Taubman was able to provide these stakeholders more than had he waited while the store bled more of its existing capital.
UPDATE: Here is FactCheck.org going over Gingrich's criticisms.