What happened

Shares of General Motors (NYSE:GM) are falling today, down 5.8% as of 1 p.m. EDT, following disappointing U.S. auto sales results for April and news that a prominent hedge fund manager had sold his stake in GM.

So what

GM no longer releases monthly sales results for the U.S., but you don't need official numbers to know that April was grim. With auto factories -- and many dealers -- shut down amid the COVID-19 pandemic, U.S. auto sales likely fell by 50% to 55% in April, based on estimates from Cox Automotive, Edmunds, and TrueCar subsidiary ALG.

A 2020 Chevrolet Silverado heavy-duty pickup truck.

Did strong pricing on its new pickups help GM avoid a first-quarter loss? We'll find out Wednesday. Image source: General Motors.

GM may have fared a bit better than the overall market. Edmunds estimated that GM's sales fell 46.7% in April from a year ago, to about 167,339 vehicles. GM may have  managed strong pricing, even with heavy incentives and low-cost financing, thanks to its still-new pickups: ALG estimated that GM"s average transaction price in April was $41,926, up 8.4% from a year ago. 

But at least one investor is fed up with waiting for GM's stock to soar. In a letter to investors, David Einhorn of Greenlight Capital said that the fund has sold its GM stake after five years. "Our hopes that 2020 would finally be the year were dashed," Einhorn wrote. 

Now what

GM will report its first-quarter earnings results before the market opens on Wednesday, May 6. They may be somewhat better than expected: Auto investors have taken note of the fact that unlike rival Ford Motor, GM hasn't yet warned investors to expect a loss.