The stock market took an instant nosedive — and made just as instant of a recovery — in response to an alarming tweet from the Associated Press account to its hundreds of thousands of followers at lunchtime on the East Coast Tuesday. The world's leading news organization quickly said that the message above was the work of a hacked @AP account, which was quickly suspended by Twitter. (Update: Now all of AP accounts are suspended.) But any word of explosions at the White House from an outlet as trusted as the AP, apparently, is enough to mess with the markets, as you can see in this Bloomberg Terminal graph below:

The AP confirmed that its account had been compromised in a Facebook post, asking Twitter not to respond to news posted on its Twitter account in the 20-minute span in question. Officials at the White House also confirmed everything was fine — White House Press Secretary Jay Carney was giving his briefing when the message went out in the last 20 minutes — and the AP even wrote a story about itself. And a quick look at the messages sent before the false (if really scary sounding) tweet show that the style of capitalization — and alarm — is all a bit off:

Still, it's pretty incredible that a single tweet could have that much of an effect on the economy, however instant and however many major companies and outlets have been hacked of late. But the sharp market tumble might have something to do with the recent incorporation of Twitter into the stock market. Earlier this month Bloomberg Terminal added certain trusted Twitter accounts to its system in order to prevent these sort of market crashes from false information. Of course, it doesn't quite work if the verified trusty accounts get hacked.

As of right now, it's unclear who's behind the false tweet, but the Secret Service is likely all over it, as is the AP. We'll update this post with further information. 

Update 2:54 p.m.: The Syrian Electronic Army, which has been hacking twitter for months, including 60 Minutes and a BBC Weather account, has taken credit for the attack, which turned out to be a phishing attack, a very common, but very simple attack. The hackers also wrought havoc on the NPR website. The group's mission, as described by their site here, is to "show the truth about Syria." Generally that has been in the form of pro-Assad propaganda. 

Update, 2:01 p.m.: The same hacker group that exposed the financial information of Michelle Obama, among other celebrities, in March has taken responsibility for this hack, too, according to TMZ. It remains unclear if this had anything to do with the group — indeed, even TMZ is skeptical.