Tesla stock declined 5% on Monday to reach its lowest level since June 2021 as CEO Elon Musk shifts his focus to leading a turnaround at Twitter.

Musk finalized his $44 billion purchase of the social media giant late last month. Since then, several firms have halted their advertising spending on the platform, a move that has the potential to lead to huge losses for Musk.

According to Loup Ventures' Gene Munster, the growing losses at Twitter could force Musk to sell more of his Tesla stake if a turnaround isn't realized soon. 

"They have a month here to kind of kitchen sink things and get people to reset with what their products are and get advertisers to understand what their content moderation is," Munster told CNBC on Monday. "If that yields the current environment, he's gonna have to sell Tesla shares in April."

On the other hand, Tesla investor Gary Black of the Future Fund ETF, which counts Tesla as its largest holding, isn't positive about Musk's attention shift from Tesla to Twitter. Nor is he happy about reports that some Tesla employees are helping Musk stage a turnaround at Twitter.

"$TWTR news keeps getting worse. Elon's top engineers shouldn't be running $TWTR. Elon's threats aren't helping. As advertisers leave, Twitter will need to raise more $," Black tweeted on Monday. 

Tesla's slump on Monday sent the stock to a low of $196.66, and shares in the afternoon were grappling to reclaim $200, which represents a critical support level for traders. A decisive close below $200 would signal to investors that there could be further downside ahead.