SEC to require biggest traders report activity

WASHINGTON — Large traders will be required to register with the government and make available more information about their trades under a rule adopted by federal regulators.

The Securities and Exchange Commission agreed unanimously on the rule, which would take effect in 60 days. The rule is a response to the May 2010 "flash crash," when the Dow plunged more than 600 points in five minutes. Regulators say tracking large trades will make it easier to understand unusual activity in the market.

The rule applies to investors who trade more than 2 million shares or $20 million a day. It also applies to investors who trade 20 million shares or $200 million a month.