For a 5 minute window, I'd consider that tanking. It looks like there is an issue with bc.info, so it looks like traders are holding off making more decisions on this news.
That's not a tank, it's a $2 drop in price caused by ~600 BTC in volume. Just a thin order book (and arguably a good spot to buy in for a short term trade)
That didn't even cause the lowest trading price of the past 24 hours.