Waddell & Reed was 'Mystery Trader' in Market Plunge According to Reuters

According to a document which was obtained by Reuters, it was Waddell & Reed Financial Inc. (WDR) that was responsible for the market plunge. It was apparently due to a large order of e-mini contracts during a 20-minute span, and was not related to high frequency traders. About 9 percent of the volume in e-minis was related to one sale.