The U.S. Securities and Exchange Commission proposed a new rule on Wednesday that would effectively prohibit broker-dealers from providing customers with “unfiltered” or “naked” access to an exchange or alternative trading system.

The SEC’s proposed rule came on the same day that the regulator initiated a sweeping review of market structure issues in the U.S. The rule would require brokers with market access, including those who sponsor customers’ access to an exchange, to put in place risk management controls and supervisory procedures. The SEC says that the procedures would help prevent erroneous orders, ensure compliance with regulatory requirements, and enforce credit or capital thresholds, among other things.

Currently, brokers that provide “direct market access” or “sponsored access,” can give customers the ability to place orders that flow directly into the markets without first passing through the broker-dealer’s systems and without being pre-screened by the broker-dealer in any way.

The SEC says that these arrangements create the potential that financial, regulatory and other risks associated with the placement of orders are not being appropriately managed. “In particular, there is an increased likelihood that customers will enter erroneous orders as a result of computer malfunction or human error, fail to comply with various regulatory requirements, or breach a credit or capital limit,” it notes.

The SEC’s proposed rule would require broker-dealers to establish, document and maintain a system of risk management controls and supervisory procedures reasonably designed to manage the financial, regulatory and other risks related to its market access, including access on behalf of sponsored customers.

The commission also approved a new Nasdaq rule that requires broker-dealers offering sponsored access to Nasdaq to establish certain controls over the financial and regulatory risks of that activity.

“Unfiltered access is similar to giving your car keys to a friend who doesn’t have a license and letting him drive unaccompanied,” said SEC chairman Mary Schapiro. “Today’s proposal would require that if a broker-dealer is going to loan his keys, he must not only remain in the car, but he must also see to it that the person driving observes the rules before the car is ever put into drive.”