What happened

Battered Boeing (BA -2.39%) stock took another tumble Thursday, and is down 6.2% as of 1:30 p.m. EDT.

But why is Boeing down? Honestly, who knows.

Boeing 737 on the tarmac

Image source: Getty Images.

So what

There's no news specifically affecting Boeing on the newswires today. No earnings. No analyst downgrades. Not so much as a price target revision downwards. And yet, Boeing is down nonetheless.

This probably has something to do with the coronavirus. (These days, what doesn't?) As my colleague Lou Whiteman just pointed out, airlines such as United are reporting air travel passenger declines of as much as 97% in the first two weeks of April.

Now what

With demand that low, it doesn't sound like United's going to need to buy many replacement airplanes from Boeing anytime soon. Indeed, Lou thinks we're probably looking at "a slow, multiyear recovery as the companies work through a probable recession."

In the meantime, Boeing is rolling down the tarmac and preparing to deliver a big batch of probably bad news in its first-quarter earnings report less than two weeks from now. Sales, according to Yahoo! Finance estimates, are likely to be down as much as 23% year over year, and earnings, nonexistent.  

Given the state of the economy, and the state of the airline industry in particular, investors can be forgiven for being a bit nervous about that today.