Joe Gebbia, a co-founder of Airbnb and a Tesla director, just bought $1 million of shares of the electric-vehicle firm.

The launch of a $25,000 autonomous vehicle would be a huge inflection point for Tesla's recently stagnating growth. And according to many estimates, a robotaxi service could add hundreds of billions of dollars to the company's valuation. The problem is that Tesla's already priced at a premium, trading at 9.4 times sales even after the correction.

Tesla shares are regaining some ground today ahead of the company’s first-quarter earnings report, due after the close. After dropping nearly 6% on Monday, shares of the electric vehicle maker were up close to 5% Tuesday morning.