Many industry insiders and analysts contend that companies backed by private equity will not suffer nearly as much as those in the late 1980s because the firms pushed for better financing conditions that allow them to keep operating even if they cannot make their debt payments.

For example, in an effort to save cash, six of Apollo’s portfolio companies, including Claire’s Stores, Harrah’s and Realogy, have announced this year that they will pay some of their bonds’ interest by issuing more debt.

Mr. Kaplan said he believed that while “it isn’t going to be pretty,” today’s deals “are much less fragile and used less leverage.” He contended that “on a relative basis to investment banks and hedge funds, private equity may be in a better place” because of its long-term focus.

Stephen A. Schwarzman, chairman of Blackstone Group, remains committed to the future of private equity. “The people rooting for the collapse of private equity are going to be disappointed,” he said. While some companies may find themselves in trouble, he said, many more will be able to ride out a downturn in the economy because of the less restrictive financing conditions that banks agreed to earlier.

Image Stephen A. Schwarzman of the Blackstone Group says firms like his can ride out an economic downturn. Credit... Shannon Stapleton/Reuters

He added that he believed that now may be the best time for private equity because of the investment opportunities amid the crisis. “Historically, downturns are when the most money gets made,” he said. Shares of Blackstone are hovering at around $10, down from the $31 they were at when Blackstone went public in June 2007. (Fortress Investment Group, another big firm, is trading at $4.90 a share, down from its initial price of $35 in February 2007.)

Mr. Lerner, of the Harvard Business School, said that trouble among private equity firms would probably “precipitate hard questions about the compensation and fee structure” in the industry. The firms generally take fees of 2 percent of all money managed and 20 percent of profits. “I would not be surprised if they try to head off the criticism by returning capital,” he said.