Mutual fund providers are jumping onto the exchange traded fund bandwagon. However, there are still some holdouts among the top open-end fund managers.

Of the top 20 mutual fund providers by assets under management, American Funds, Dimensional Fund Advisors, Dodge & Cox, Lord Abbett, Janus and American Century have not pursued their own ETF offerings, reports Jackie Noblett for the Financial Times.

“For us the issue remains transparency,” American Funds spokesman Chuck Freadhoff said in the article.

ETFs are known for their daily transparency. The attribute helps authorized participants, or market makers, create or redeem ETF shares so that the price matches that of the net asset value of the fund’s underlying holdings. Consequently, active managers are loathe to switch over to a transparent ETF structure, potentially revealing their secret sauce to potential front runners.

However, Eaton Vance, T. Rowe Price, Invesco PowerShares, Vanguard Group and BlackRock have been pushing the Securities and Exchange Commission to launch non-transparent active ETFs to help address the front running issue. [Waiting on the SEC to Approve Non-Transparent Active ETFs]

“By this time next year, the industry will start to look different,” Bill Donahue, managing director at PwC, said in the article, predicting that the number of firms that don’t have an ETF, along with their traditional mutual fund line, will be “more the exception than the rule.”