New Rules for Broken Stock Trades Proposed

Federal regulators have put forward proposed new rules spelling out when and at what prices stock trades would be canceled, in a response to last month's "flash crash" in the market.

The Securities and Exchange Commission said Thursday it is publishing for public comment the rules proposed by the major U.S. exchanges and the brokerage industry's self-policing arm. Under the proposal, there would be a series of thresholds for canceling trades when prices diverge from the last sale before pricing was disrupted. The higher the value of a stock, the smaller the divergence would have to be to trigger a cancellation.

Nearly 21,000 trades were canceled in the May 6 market plunge. There now is no clearly defined standard.