The point is that Bob is not putting in a $51m sell order when exchanges average $1m a day. You'll be hard pressed to find people with that kind of money. Entir

The point is that Bob is not putting in a $51m sell order when exchanges average $1m a day. You'll be hard pressed to find people with that kind of money. Entire funds have less than that, the Bitcoin Investment Trust for example, ran by Barry Silbert's Second Market, is a $36m asset fund. Anyway, you can argue the exact numbers, I just mentioned some hypothetical ones. Fact is that big whales and spoofing does exist, it's a well known phenomenon on bitcoin exchanges, and of course is not unique to bitcoin. It's been part of any market place for a long time, it's called spoofing and it's usually illegal because it's manipulative and effective. As for whether there is risk, yes of course there is risk. People still do it and it appears people have been successful. Especially in immature markets.