The asset management arm of TD Ameritrade has been quite active recently. And it appears to be ramping up for a bigger presence in the exchange-traded funds market.

In a filing dated April 20, the company has amended past requests for new ETFs through its TDX Independence Funds group. Among the main changes is the creation of a new family of ETFs to be marketed and operated as the X Funds family.

Earlier this month, TDX Independence Funds asked the Securities and Exchange Commission to make Amerivest Investment Management the investment adviser to its series of five target-date ETFs. The filing also made it clear that struggling XShares Advisors could be removed from the family in the future. (See story here.)

A spokeswoman for TD Ameritrade declined to comment on Tuesday about action regarding any pending filings.

The most recent document explains that X Funds is an open-end management investment company organized as a Maryland corporation. X Funds filed with the SEC a registration statement last October. But it hasn't been approved yet.

"X Funds ... will offer a number of different series of funds with distinct investment strategies in an exchange-traded fund format," said the filing.

It added that X Funds currently has two portfolios. Presumably, those two portfolios would be the first X Funds out of the gates. Those are:

• The Nations Large Cap Enhanced Covered Call ETF. It's expected to be subadvised by Esposito Partners LLC, according to the filing.

• The CRB-Research Global Energy Efficiency ETF.

Neither fund seems to actually be all that new. The global energy ETF's request was originally made last fall. In the new filing, XShares is still listed as its adviser. But as indicated by the filing, it's now listed as one of the X Funds' portfolios.

The CRB-Research Global Energy Efficiency ETF would track an index that includes companies that generate at least 50% of their revenues from related activities and have a market cap of at least $250 million and a three-month average daily trading value of $2 million.

The index's components fall into five different buckets: grid/utility, buildings, lighting, equipment/industrial and transportation.

The Nations Large Cap Enhanced Covered Call ETF will do just as its name implies. Its benchmark will reconstitute monthly, although the fund might do so quarterly, according to the filing.

Last year, XShares filed to offer a similar type of fund. That was the Fortress Large Cap Enhanced BuyWrite ETF. Besides writing options on its underlying index, the Fortress fund would sell put options on credit spreads. It's not clear from the filing whether the new ETF would replace the Fortress fund.

One hint is that Esposito Partners LLC was listed as the subadviser on the portfolio, handling day-to-day duties of its management. The Dallas-based firm is also named in the new filing as subadviser for the proposed Nations Covered Call ETF.

(The new filing also explains that the former-TDAX Independence Funds have dropped the letter "A" from its name, a development reported earlier on IndexUniverse.com.)

You can find the filing here.