Warren Buffett, chairman and CEO of Berkshire Hathaway (BRK.B), wasn't doing much buying during the first quarter, which ended just before the economic impact of the coronavirus really set in. But he sure did a lot of selling.

Buffett has dumped shares in 21 stocks since the start of the year. For the most part, the Oracle of Omaha has merely trimmed BRK.B's positions. Reducing risk and raising cash are certainly prudent moves when facing the unprecedented uncertainty that we are now. In a few cases, however, Buffett sold the great majority or entirety of Berkshire's positions in some of its biggest and best-known holdings.

On the other side of the ledger, Buffett made just one buy in the quarter, adding a modest amount to a well-known regional bank.

We know what the greatest long-term investor of all time has been doing because the U.S. Securities and Exchange Commission requires all investment managers with more than $100 million in assets to file a Form 13F quarterly to disclose any changes in share ownership. These filings add an important level of transparency to the stock market and give Buffett-ologists a chance to get a bead on what he's thinking.

When Buffett starts a new stake in some company, or adds to an existing one, investors take that as a vote of confidence. On the other hand, if he pares his holdings in a stock, it can spark investors to rethink their own investments. The fact that Buffett was fearful rather than greedy as the market plunged in Q1 underscores how challenging it is to make investing decisions these days.

Here's the scorecard for what Berkshire Hathaway bought and sold during the three months ended March 31, 2020, based on the most recent 13F that the company filed on May 15. And remember: Not all "Warren Buffett stocks" are actually his picks. Some smaller positions are believed to be handled by lieutenants Ted Weschler and Todd Combs.

PNC Financial Services

Getty Images

PNC Financial Services (, $97.25) claims the honor of being the only stock Warren Buffett