Hedge funds play with about 2 trillion dollars.

Today a fifth of all hedge funds had a must sell order.
In other words they had to pay a client or a bookie.

the problem was...there were no buyers...so the price kept going lower. OTher holding were sold to cover some of these losses so the DOW went down 800 points at one point today, then slowly crept back up to only 500 points down.