In March, the board of California Public Employees’ Retirement System (Calpers) approved a plan that could channel up to $20 billion into private equity startups and corporate buyouts over the next ten years—in an effort to boost returns and cover the benefits promised to its 1.9 million members. This according to an article by Wall Street Journalcolumnist Jason Zweig.

“Over the ten years through June 2018,” Zweig reports, “private equity was Calpers’ best-performing asset, returning an average of 9% annually, compared with 6.7% on public stocks” (Preqin data showed that the median pension fund earned 8.8% on private equity and 6.8% on public stocks). “Still,” Zweig notes, “the future for private equity might not be as lucrative as the past, with money gushing in and with buyouts priced near their highest levels in the past decade and a half.” He cites comments from industry experts that echo the concern, including from Preston McSwain of Fiduciary Wealth Partners: “For society’s sake, we hope returns on private equity will be good for these pension funds.”

But Calpers’ chief investment officer Ben Meng said in an interview that private equity is a “more know-who market than a know-how market. We can get access to the best-performing managers most of the time.” Not investing or keeping funds in cash, says Meng, is not an option for Calpers, but he is aware of the downside. “This may or may not work now,” Meng said, adding, “We won’t know unless we try. People should be mindful of the risks.”