Snapchat, written down 25% by Fidelity ($31 -> $23)

Unfortunately that's probably not the correct way to estimate Snapchat's value based on Fidelity's assessment. Since Fidelity probably has a liquidation preference—and a recent one, at that—the implied new valuation of the company is much lower.

Depending, of course, on a whole bunch of details about the investment and Fidelity's assessment that I personally don't know.