Mutual funds have been warily eying at the upstart exchange traded fund industry. After Eaton Vance’s proposed exchange traded managed funds structure, we could see major changes in the fund industry.

ETMFs come with low-cost attributes that ETFs enjoy, but unlike ETFs, ETMFs are designed to “disclose their holdings in full at least once quarter with a lag of not more than 60 days,” according to Eaton Vance’s filing, reports Mary Schroeder for Traders Magazine.

Moreover, unlike ETFs, ETMFs will trade at prices based on the net asset value at the market close each day. “Because ETMFs will trade at prices based on their NAV, investors will be able to buy and sell shares at a known premium or discount to NAV,” according to the filing. [Newfangled ETFs from Eaton Vance Would Deter Frontrunning]

The ETMF is the industry’s response to the growing interest for actively managed ETFs, which require to disclose holdings on a daily basis. [Eaton Vance Proposes New Active ETF Structure]

“A good portfolio manager values the research that they’ve done in terms of determining which securities they want in their portfolio and the idea of having to reveal changes every day doesn’t work for them,” said Gary Gastineau, principal at ETF Consultants.

However, the lack of transparency could be a major hurdle for market makers that help create and redeem ETF shares through arbitrage opportunities in a normal trading day.