The rule defines which companies trading derivatives will be subject to a stricter regime created in the 2010 overhaul of financial laws. Most companies that deal derivatives will be exempt.

Critics say the changes will allow major Wall Street banks to continue to dominate the $700- trillion derivatives market. The Commodity Futures Trading Commission approved the rule on a 4-1 vote.

Taken together, "these rules are intended to make the financial system safer, and the derivatives markets fairer, more efficient and more transparent," SEC Chairman Mary Schapiro said before the vote.

The Proposed Rule release was accompanied by a white paper titled “Use of Derivatives by Investment Companies,” prepared by SEC staff in the Division of Economic and Risk Analysis, which is ...