I agree with Cutten. Important things to note: * Risk adverse trades (including but not limited to declining equities) were on before 2pm ET * Then to paraphrase Cutten, the sellers became even more aggressive, and the buyers either reduced their bids or pulled them completely * The fat finger stuff may have happened or not, but it's not really relevant, apart from making a good story for the evening news. Also a good summary of yesterday's action in this article http://www.zerohedge.com/article/dissecting-crash