Wall Street's main regulator is reportedly very concerned about digital engagement practices used by brokerage firms to encourage stock buying.
Comments by Gurbir Grewal, SEC enforcement director, signal a crackdown on practices critics call gamification of investing, though he refused to discuss any investigations during a hearing on Tuesday.
A year ago, the SEC said it was concerned that game-like features encourage excessive trading, putting investors at risk.
Under existing rules, when a firm offers investment advice or recommends securities it is required to put clients' interests first.
"Gamification is a huge concern," Grewal told members of the House Financial Services Committee's Subcommittee on Investor Protection, Entrepreneurship and Capital Markets.
"I’m concerned when gamification crosses the line into a recommendation," he added, reports Bloomberg.
Grewal said when firms use digital nudges to influence customers, the SEC could take action as they do not comply with rules requiring them to act in clients' best interests.
The SEC announced last month that it would propose new rules this year as part of a broader effort to make the US$45trn US equity market more transparent.
Nascent brokerage platforms such as Robinhood have been a relatively new development in the gamification of the financial sector.
A troubling conflict of interest has been identified between financial gamification and order flows, which have caught the attention of the US SEC.
Gamification in financial markets has also come under scrutiny by the EU's financial watchdog.