Well I know back in the 80's I was going to short an oil stock and my broker told me major players had a bid under that stock at a certain price and the world could come to an end and that price wouldn't break below that price point. And even with a heavy selloff in Oil stocks that stock never did break down. Don't know how much money it would take to manipulate a market but there are more innovative ways to finance positions today than ever before. Just look at option expiration week and see the stock market Indexes rise or fall to a level that will cause the maximum financial damage to both the put AND call owners. Quite a coincidence each month. Don't think it's just bad luck.