(this article originally appeared in Investment News)

The Securities and Exchange Commission will let a rule that eases principal trading requirements for certain financial advisers expire at the end of the year.

The decision marks the end of a temporary rule that had been extended several times since it was first adopted in 2007.

“We understand that few firms today are relying on [the] rule,” David Grim, director of the SEC Division of Investment Management, wrote in an Aug. 19 letter to Ira Hammerman, executive vice president and general counsel of the Securities Industry and Financial Markets Association.

Under the regulation, investment advisers who are dually registered as brokers and registered investment advisers can conduct principal trades for clients in non-discretionary advisory accounts without having to obtain transaction-by-transaction written disclosure and consent.

Instead, the disclosures could be made on a prospective basis and either orally or in writing. Other conditions would have to be met as well.

The measure was proposed following a court decision that vacated an SEC rule allowing brokers to manage fee-based brokerage accounts without registering with the agency as investment advisers.

In its previous extensions of the rule, the SEC said that it wanted to allow the commission more time to develop a regulation that would raise advice standards for all retail accounts and to harmonize adviser and broker-dealer rules.

The Dodd-Frank financial reform law gave the SEC the authority to propose a fiduciary-duty rule but the agency has not been able to advance a measure.

Letting the interim rule on principal trading expire may indicate further delays on a broad advice rule, according to Duane Thompson, senior policy analyst at Fi360, a fiduciary training firm.

“You could read a lot of different things into this letter,” Mr. Thompson said. “That could be a signal that the fiduciary rule is dead in its tracks for the time being.”

SEC spokesman John Nester declined to comment beyond the language in Mr. Grim’s letter.

The interpretations of the letter varied.

David Tittsworth, counsel at the law firm Ropes & Gray, said that the SEC is trying to streamline its rule inventory.

“This is more of a clean-up effort than some sort of significant shift in policy,” Mr. Tittsworth said. “I don’t think this means the SEC is closer to bringing forth a fiduciary rulemaking.”