When you’re No. 2 in ETF trading, you have to try harder.

Nasdaq, as the No. 2 marketplace for ETFs behind the New York Stock Exchange’s electronic platform, NYSE Arca, is known for putting more ideas “out there,” and right now, it’s got a proposal pending with the SEC for a new type of order for U.S. equity ETFs called an “iNAV Pegged Order.” If the SEC gives it the nod, it will be a first of its kind.

With U.S. equity ETFs, their iNAVs, or intraday net asset values, are automatically adjusted every 15 seconds based on the current market value of the stocks in their portfolios.

What the Nasdaq is proposing is that investors be allowed to put in orders “pegged” to a U.S. equity ETF’s most recent iNAV. “As the iNAV changes, so move the iNAV Pegged Orders,” the Nasdaq stated in its SEC filing, made on October 12. Nasdaq also noted “a Pegged Order may have a limit price beyond which the order shall not be executed.”

And the point of instituting this order type, Nasdaq said in its pitch to the SEC, is that “relative to the current intraday order entry/execution order types, the iNAV Pegged Order type would allow certainty of execution with a greater correlation to the ETF’s fair value for those seeking to invest on a more informed basis.”

“I think it’s a good idea,” says Michael Rawson, an ETF analyst at Morningstar in Chicago. “It’s like a limit order, but pegged to the current iNAV of a fund, and that makes sense,” he says.

But Dave Nadig, the director of research at IndexUniverse in San Francisco, sees a number of potential problems. “I think it’s got its heart in the right place, but the devil’s in the execution,” he says.

First of all, it applies only to the ETFs that are strictly invested in U.S. equities because those are the only ones where it’s possible to get an intraday NAV that is “close to being accurate,” he says. Therefore, the ETFs that hold some mix of U.S. and international stocks, or stocks and bonds, would be excluded, and that narrows the list of eligible ETFs to “a few hundred,” he notes.