08/15/2009 05:12 am ET Updated May 25, 2011

Electronic Trading: Robot Wars Hit Wall Street

Dramatic market moves have become commonplace, and those looking for a fundamental explanation are missing a significant structural change: The majority of stock trades now originate with so-called "high frequency" funds, which use computers programmed with obscure mathematical correlations to execute trades. The computers trade in and out of stocks at light speed, sans human intervention -- no trader, no economist, no chart tracker. These funds argue that computers aren't swayed by emotion, and naturally move much faster than a person ever could.