This issue has been around for some time. 20-some years ago I examined (i.e., audited) a major public pension plan. One of their private equity funds had a large investment in several Conseco private, bespoke, preferred stocks (PIPE). Dividends were either PIK'ed or matched the common stocks'. In other words, the preferreds' value was inseparable from the common. As Conseco descended into bankruptcy, the GP maintained their original cost valuation.

There is something of a conundrum in placing a market value on something for which there is no market, a problem for which I've some sympathy (and offered some solutions at the time). Secondaries help, but they've nothing like the volume of the NYSE or NASDAQ, and there's often "a story" attached to the sale. The flip side of that conundrum is determining the intrinsic value of marketable securities, equities. (Hello Graham & Dodd & Buffett!) These issues offer amply fodder for CFAs analyze and debate!