TDX Independence Funds Inc., which is controlled by TD Ameritrade, is asking the Securities and Exchange Commission for permission to make Amerivest Investment Management the investment adviser to its series of five target-date retirement exchange-traded funds.

Amerivest is perhaps best known by ETF investors for its commission-free trading accounts. The TD Ameritrade unit charges its ETF customers set fees based on asset levels in exchange for asset allocation advice.

In the request, dated April 10, current adviser XShares wouldn't be immediately removed as adviser to the TDX Independence funds.

But the filing says that TDX believes that "it is foreseeable that Amerivest may replace XShares as the investment adviser to TDX Funds."

The filing states: "Applicants seek the relief so that, in the circumstance where XShares no longer serves as investment adviser to the funds, the TDX funds and Amerivest may rely on the order granted ... "

The filing goes on to explain that TDX has brought Amerivest on board as a subadviser to the funds. No date was given for that shift.  

Interestingly, the filing also notes that Mellon Capital Management Corp. is a subadviser to the funds as well—and apparently will continue in that role. (Another note, which wasn't mentioned in the filing but confirmed by TD Ameritrade on Wednesday, is that TDX Independence has dropped the "A" from its name for marketing reasons. It used to go by the TDAX brand name.)

The shift would seem another not-so-rosy sign for struggling XShares. Last summer, it closed 15 ETFs targeting subsectors in health care. (See related article here.)

In November 2008, it announced the remaining four HealthShares would close by year-end. (See related story here.)

Besides the five target-date retirement funds, that left XShares with one other ETF. That's the AirShares EU Carbon Allowances Fund (NYSE Arca: ASO), which was launched late last year. (See related article here.)

The TDX Independence series was the first of its kind in the ETF market when it launched in 2007. The venture between TD Ameritrade and XShares was designed to capitalize on the popularity of target-date and life cycle funds with mutual fund investors.

But the family, which actually includes four pure target-date funds and another that acts more like a life cycle portfolio, had attracted a total of about $114 million through the first quarter, according to Morningstar data.

Last November, iShares entered the target-date market with the launch of its own series. (See related article here.)

Earlier this year, start-up provider FocusShares filed to launch its own line of eight target-date ETFs. (See related story here.)