Tesla CEO Elon Musk offered to buy the social-media platform Twitter on Thursday, sending shares of the carmaker lower. 

Investors might be worried about distraction for Musk as Tesla (ticker: TSLA) ramps up production at new plants, but there are other potential concerns as well. 

Twitter (TWTR) stock rose early in the day, but was down shortly after noon, falling 0.3% to $45.72, and dropping further away from Musk’s $54.20 offering price—a number  

that hints a Musk’s fondness for marijuana memes. Tesla's (TSLA) stock was down more than 3%. The move-in Twitter stock added about $1 billion in market value earlier in the day.  

Now the value is down a little. The move-in Tesla stock, which is roughly 25 times more valuable, takes away about $37 billion in value.  

Combined, the companies are worthless after the bid. The initial move in Twitter means that investors think it is likely that Twitter’s board will reject Musk’s bid.  

Musk, for his part, said this was the best offer in his communications with Twitter leadership. Still, Twitter investors are probably happy with Musk,  

even if they are nervous about Thursday. Twitter stock has risen about 16% since Musk disclosed his stake in the social media platform.  

Tesla investors have little to celebrate. The stock is down almost 9%, while the S&P 500 and Nasdaq Composite are off about 3% and 6%, respectively. 

Tesla stock is typically more volatile than the market. That is one reason shares are down more.  

But Tesla investors might also be a little concerned about what Twitter means for Musk. 

There is the possibility of distraction. Twitter might steal Musk’s focus away from Tesla during a time when EV sales are ramping up across the globe.  

Tesla is expected to see rapidly rising sales—and competition—in the coming years. The distraction might also be making investors consider who could run Tesla other than Musk. 

Roth Capital analyst Craig Irwin told Barron’s that Tesla is Musk and Musk is Tesla.  

He doesn’t believe there is another executive at the company that can drive Tesla forward like Musk can.