The U.S. Commodity Futures Trading Commission voted 4-1 Wednesday to approve a proposal on how customer money is treated for over-the-counter derivatives called "swaps" that many market participants have argued should be stronger after MF Global revealed risks in the current system.

The rule approved Wednesday would require FCMs to keep customer collateral in an account segregated from the FCM's own property. However, the rule allows FCMs to keep all of their swaps customers' collateral in a single account. The rule includes requirements in the case of bankruptcy and customer shortfalls and how that money will be transferred back to customers.

CFTC Chairman Gary Gensler said in his opening statement that the commission is considering both further protections for the swaps market as well as perhaps eventually extending those protections to the futures market.

The new rules can be found here.