His rival Joe Ratterman, the chief executive of Bats Exchange, agrees.

FORBES: Lessons of a Market Swoon

In an e-mail Tuesday, BATS Chief Executive Joe Ratterman, who took over for founder David Cummings last month, said U.S. markets are "on the edge of a tipping point, " pushed there by the embrace of all-electronic trading.

FORBES: Intelligent Investing Briefing Book

"There is a possibility of creating a two-tiered market, where the best quotations from specific markets are made available to a limited number of market participants, " wrote Joe Ratterman, Bats chief executive, in a memo to traders this month.

FORBES: Exchanges