After volatile pricing of exchange-traded funds in August last year forced trading halts and an investigation by U.S. regulators, an early champion of the industry is now raising concerns about the products he helped build.

Gary Gastineau promoted ETFs to investors because of their cost savings when he was an American Stock Exchange executive in the 1990s and he oversaw the listing of the first U.S. funds tracking industry sectors and foreign markets, but now he now argues that many funds cost more than investors realize.

Some of the concerns will be detailed in an article to be published this weekend in the Journal of Portfolio Management.

In an interview, Gastineau now says he wants the U.S. Securities and Exchange Commission to police data published by fund companies to ensure it is not misleading and he is also asking the SEC to deny applications for some new ETFs.

Securities lawyers expect ongoing public comments will inform a new rule governing ETFs, but the timing is unclear. Such a rule has long been on the industry's wish list because it could make launching new ETFs easier.

"Many ETFs just don't work very well," Gastineau, now an industry consultant, told Reuters in an interview.

Gastineau claims investors cannot determine whether an ETF price is fair value and that exchanges favor Wall Street trading firms over individual investors.

Further, some new kinds of ETFs may expose investors to costs, taxes, and trading halts that may undermine their ability to sell when they want to, he said.

Gastineau, 76, has some standing in the industry and his letters to government officials have informed policy before. The SEC cited Gastineau's research or correspondence six times when, in 2014, it tabled a proposal to launch a new kind of ETF that would compete directly with NextShares, a hybrid of mutual funds and ETFs that price once daily.

But Gastineau helped invent NextShares, a type of fund from which he still earns revenue, and he may profit from preventing competition, creating a potential conflict that could discount his views.