This year Twitter is expected to make 13 times as much profit as Snap. And yet right now, each company is trading on the stock market at roughly the same market capitalization: $25.5 billion. Investors are either overenthusiastic about Snap’s prospects—or too pessimistic about Twitter’s (or possibly both).

The market may have it right on Twitter, but not on Snap. Investors appear to have forgotten its past stumbles, with both its app changes and its management turnover, and are counting on everything going right moving forward. That’s a risky bet. Fourth-quarter 2019 earnings reports coming today from Snap, and Thursday from Twitter, will provide an updated picture of how the two businesses are faring.