someone just sold a bunch of shares tanked from 3.67 to 3.57
Actually if you check out the chart or the high/low, It went to 3.67 to 3.46 to 3.56 in a blink (technical term). Think of it as a mini flash crash.
Maybe someone at Baker Bros tried to sell 10 shares to buy doughnuts and rested on the 0 while he sneezed. Dump 50K and watch the market sell orders trigger.
Hence the stop limit orders I use on something I want to keep.