You are correct in your timing.
I saw -450 or so, got up to tell a friend. He was on the phone, so I walked by to my desk and it was around -600. Two minutes later -830.
Went back to his desk and google finance was frozen.
I’m hearing on CNBC that the sharp plunge may have been from somebody at a big firm pushing the B key for billion instead of the M key for million. I don’t believe that for one second. Those firms should all have software to check for input errors like that and stop them from being sent into the market. My trading workstation has that kind of software and it’s just a java-based workstation from a firm where anyone can set up an account. I have it set to stop any trades greater than 200 shares and ask me for confirmation on any share amounts above 200. That way I can’t accidentally type in 2000 instead of 200.
Someone is spreading BS rumors on Wall Street. This looks more like a breakdown in orderly functioning of market maker firms. I’ve seen a great deal of that behavior before in the first 15 minutes of the day, but never to this extent in the middle of the day.