Wow! Generally speaking it was predictable because as far as I know the institutional investors and smart private investors did not buy the shares from NASDAQ and S&P500 on the highs because it was obviously for everybody that shares were overheated. Companies are still buying back its own shares but it will be over soon I am sure that a trader who opens a short position on NASDAQ or S&P500 just in time of inception of falling will earn much but it need to be carefull because any short position is very dangerous.