I think a better financial attack with people who have huge financial resources would look something like this:

1) wait for bitcoins to hit a low ($30 for example)
2) start to enter the market in small chunks
3) accumulate a large significant holding of BTC let's say 30-50% of entire outstanding value (of course this could take a significant amount of time)
4) wait for prices to drift higher ($265 for example)
5) start selling like crazy in large chunks to move prices down
6) people start to panic as they see prices dropping rapidly and sell
7) now price is nearing a low ($30 again)
repeat

The only thing that prevents this from happening is 1. regulations 2. a huge huge size of the entire BTC market