Some of the world's most well-known private companies have lost value since the pandemic's start, according to their mutual-fund backers, securities filings show. Even before the pandemic hit, a survey of venture capitalists found that a majority believed unicorns were "significantly" overvalued. Bankers and valuation experts see a potential quick fix to falling valuations: SPACs, which have taken Wall Street by storm over the last month. Visit Business Insider's homepage for more stories. Palantir, Airbnb, WeWork, and Sweetgreen have all had their valuations cut in recent months by the biggest asset managers in the world.