Remember the May 6, 2010 Flash Crash – that caused the Dow to drop 1000 points in manner of seconds (and almost immediately completely rebound)?

It was caused by a high-frequency trading bot. The Atlantic has an enjoyable write-up on the these bots – turns out – we don’t know what the hell they’re trying to do.

The software engineer profiled in the article posts some of more bizarre trading behavior these bots on his Market Crop Circle of the Day blog.

Super fun stuff.