Tesla fell 3.8% at 10:53 a.m. Thursday in New York. Through Wednesday, the stock had dropped about 5.7% since Musk revealed a stake in Twitter last week, more than double the decline in the broader S&P 500 Index over that time.

“As the CEO of a trillion-dollar company, Elon Musk should focus on Tesla and not waste time attempting to acquire and manage a $43 billion company,” said David Trainer, CEO of investment-research firm New Constructs, in an email.

Tesla faces “significant competition” as major automakers are catching up on innovation in electric vehicles, Trainer said. Shareholders may be worried that Musk — the world’s richest person, according to the Bloomberg Wealth Index — would be pulled away from operations if his Twitter bid is accepted. Musk controls product decisions at Tesla and plans to start production of the Cybertruck, Semi and next-generation Roadster next year.

At the same time, Musk has a strong hand in SpaceX, which launched the first space flight with private astronauts last week. The company is a major contractor for NASA and plans the delayed Crew-4 launch to the International Space Station as soon as April 23.

Even if he has executives to help run his different enterprises, Musk is anything but a delegator. He has described himself as a “nano-manager” and handles almost all major decisions at his companies. When Tesla was having trouble getting the Model 3 production line going, he famously slept at the factory to oversee assembly.

Musk said Thursday that he doesn’t have confidence in Twitter’s current management, suggesting he isn’t likely to be hands-off if he succeeds in buying the company.

Another risk for Tesla shareholders is that Musk could sell some of his stake in the automaker to pay for the Twitter deal, according to Wells Fargo analyst Colin Langan. Musk owns about 17% of Tesla shares, valued at about $170 billion, and Langan said in a research note that offloading some of them to pay for the takeover may put pressure on the stock price.

Musk’s offer for Twitter is conditional upon “completion of anticipated financing,” which Langan said implies that at least some portion of the purchase price will come from outside sources.

–With assistance from Katrina Lewis and Ed Ludlow.