Supposedly it has to do with a kr exchange listing steem a few days ago. Then the kr people jumping on it.
I have been chasing the price down in the market for a few days now and my last buy was .221 sbd for 1 steem. I'm so grateful to the un-remembered person who told me to keep a few outrageously low buy bids in the market to take advantage of pump and dump times when they happen. Words to live by right now :)