The stark contrast between Meta and Tesla earnings reactions reveals the uncanny power of Musk's promises

• The rules are always a little different for Elon Musk.

• The Tesla CEO keeps it cool and keeps investors on his side.

• Despite his track record, Musk's promises still carry weight.

Once again, Elon Musk managed to buck expectations this week when the company's stock soared despite dismal earnings results.

Tesla quelled weeks of investor angst with Musk's word on two important future products: a long-awaited affordable model and the eventual activation of a self-driving ride-hailing fleet.

Musk did not give a timeline for when either of these things would happen (we might see one in August). Even if he did, the billionaire is famous for missing his own deadlines.

Still, Tesla's stock, which had been in a free-fall heading into Tuesday's earnings, has soared 16% in the days after. (It's still about 35% off recent highs, though).

Facebook owner Meta, on the other hand, reported relatively strong earnings for the first quarter — only to see its stock price plummet as investors worried over the cost of CEO Mark Zuckerberg's future AI ambitions.

While Musk talked cost-cutting, Zuckerberg had to warn investors the bets wouldn't pay off immediately.

Meta stock plunged in trading Thursday following the Wednesday report and is set to close down nearly 11% despite a healthy run of 27% since the start of the year.