Troubles in the retail sector and turmoil in the oil and gas industry have spurred the number of bankruptcy filings by private equity-backed companies to its highest year-to-date level since at least 2012. Through June 10, there were 41 PE portfolio companies across sectors that filed for bankruptcy protection this year, up around 193 percent from 14 in the same period last year, according to data collected by The Deal.

"PE funds, like public investors, spread their investments across various sectors," said Paul Harner, the partner in charge of Ballard Spahr LLP's restructuring practice in New York. "Notwithstanding that they've been enormously successful over the last several years, especially since the collapse in 2008, it's inevitable that they're going to be caught in some troubled situations."