no one sets the price other than the people buying and selling on the exchanges and there probably ain't very many who do it full time. but all it takes is one surge of serious demand and the coins they use to play are eaten up and never returned.
in the early days on mt gox there was one guy who was putting up walls of thousands of coins, the chart was a vertical line into infinity. some other guy came along, bought it all and he was never heard from again.
I agree, it can happen if say 5 whales gather at August and do their move
Low trading volume and it will be easier for them to push the prices and
essentially "play" with the rest people trading at those looping periods.