Lower Trading Costs Only Benefit Long-term Investors If They Are Not Offset by More Trading

The NYT had an interesting article on the growth of high-speed trading on U.S. stock exchanges. While the piece notes the risks that these trading system can pose to long-term investor by taking profitable opportunities ahead of them, it reports the industry's claim that it benefits long-term investors:

"the new trading sites and high-speed trading firms have managed to fend off critics by pointing to benefits that long-term investors have derived from the sophisticated markets.

One of the mo...