American Funds, one of the largest issuers of actively managed mutual funds, is the latest fund giant to file plans with the Securities and Exchange to possibly list non-transparent actively managed exchange traded funds, an investment vehicle regulators have yet to approve.

Unlike traditional ETFs, most of which disclose holdings on a daily basis, active non-transparent funds would only disclose holdings periodically in an effort to deter front-running.

“The cloaked nature of these ETFs appeals to portfolio managers who are concerned about tipping their hand to other market participants about what they are buying and selling,” reports Karen Damato for the Wall Street Journal. The Journal originally reported that American Funds is mulling a foray into the ETF business.

Some of the largest asset managers and mutual fund companies have previously filed plans for active non-transparent ETFs, including State Street (NYSE: STT), BlackRock (NYSE: BLK), Eaton Vance (NYSE: EV), T. Rowe Price (NasdaqGS: TROW) and Precidian Investments. BlackRock and State Street are the two largest U.S. ETF issuers. [Waiting on SEC Approval of Non-Transparent Active ETFs]

Additionally, Eaton Vance Management has filed with the SEC to offer “exchange traded managed funds” or ETMFs that would not disclose holdings daily. According to the SEC filing, ETMFs would act as a new type of open-end fund that provides confidentiality of the current portfolio holdings while maintaining the cost and tax efficiencies and protections associated with ETFs.

ETMFs would trade on an exchange, with prices linked to the fund’s next-determined daily net asset value, or NAV.