Hopes for these flash boys are growing dimmer.

The Securities and Exchange Commission said Friday it will delay IEX’s bid to become a full-fledged stock exchange and pointed to a recent tweak to its business model as the reason.

The extension — the second since the trading upstart featured in Michael Lewis’ “Flash Boys” applied for exchange status in September — comes over IEX’s objection. The SEC now has until June 18 to approve or deny the application.

IEX wants to put a 350 microsecond “speed bump” on stock orders as a way to keep out ultrafast traders from taking advantage of slower investors.

Rivals, including the New York Stock Exchange and trading powerhouse Citadel, called the speed bump unfair and claimed it would violate existing rules that require exchanges to provide instantaneous quotes.

IEX also took even more heat for a plan that would allow its own brokerage clients to bypass the speed bump. Under pressure, the firm, run by Brad Katsuyama, backtracked and said all orders would be subject to the delay.

The SEC said it is evaluating the revised proposals and “whether they constitute unfair discrimination, or impose an unnecessary or inappropriate burden on competition.”

The agency also called for more public input on IEX’s application, which has already drawn hundreds of comment letters. An IEX spokesman declined to comment.