What happened

Booking Holdings (NASDAQ:BKNG) gave investors a bit of a shock this morning, finally announcing its Q3 earnings release date, and it's going to be...today!  

Or, more precisely, tonight, after close of trading.

Now, you might think investors would be pleased at the news that they'll soon get to hear how well Booking Holdings is doing -- but they're not. Instead investors are spooked, and they've sold off Booking Holdings stock to the tune of 7.6% as of 12:20 p.m. EST.

Cartoon characters confused by a falling stock chart

Image source: Getty Images.

So what

What's to explain this curious reaction to Booking's mere announcement that it's going to announce something else in a few hours?

The reason may be traced to the earnings that rival online travel agent Expedia (NASDAQ:EXPE) announced yesterday, which featured a 22% drop in net income. Expedia stock is falling in reaction to that news (and to the two analyst downgrades that followed it).  

Investors appear to be assuming that if the travel market is bad for Expedia right now, then it's probably going to turn out to have been bad for Booking as well when it reports its own earnings tonight.

Now what

Speaking of which, heading into this earnings report, analysts are forecasting that Booking will grow its Q3 sales 6% to $5.1 billion and report an even bigger 18% jump in profits -- $44.57 per share. With such a high hurdle to clear, there's a bigger chance that Booking will trip up and fail to grow as much as expected.

At least some investors don't seem interested in sticking around to see if that happens. Instead they're selling now before things have a chance to get any worse.