Lots of FUD going around that they are insolvent and that the whole 'transaction malleability' issue was just a way for them to buy time. Some people believe that if this is truly the case then they are better off being owed fiat than Bitcoin... Seems like one big whale in particular.
Maybe you should start reading the candlestick charts better - the whale bought thousands of coins and the price went up high above $500 and then it started to drop.
Yes, that was based on some FUD on Reddit saying that someone had withdrawn coins from Gox. The drop under $300 was also likely due to more FUD on Reddit where a supposed insider claimed that Gox was insolvent and noone was ever getting their money back.
And yes, I was sitting right there and watched the spike past $500 but I've been out of the office for the last 4 hours (on my phone now) so I can only assume that if the price is under $300 then there was a big whale dumping coins, don't see how else it could happen, unless the big wall at $300 was pulled.