Whatever the error, experts have said it was very likely exacerbated by a market made more volatile by high-speed trades and automatic sale orders that are , instead of seconds or minutes with a manual system.

Earlier this year, the SEC sent a letter to brokerage houses saying it was conducting a "broad review" of the equity market structure and asking them for comments. The review would include an evaluation of equity market structure performance in recent years and an assessment of whether market structure rules have kept pace with, among other things, trading technology.

The SEC asked for comment on a wide range of issues, including high frequency trading, order routing, market data linkages, and undisplayed, or "dark," liquidity.

Financial Services Committee ranking member Spencer Bachus (R-Ala.) cautioned against taking action before the reasons for the market drop are clear. Bachus said in that the challenge is to address the problem but at the same time not destroy the benefits of an automated market.

"In my opinion, since January, the SEC has done this. The meeting yesterday with the leading trading platforms followed by the proposed initial corrective action was appropriate. They all acted in a measured way," Bachus said.