A closed-end exchange-traded fund?

That's what WisdomTree Investments seems to be proposing. In a new filing, the New York-based firm is asking the Securities and Exchange Commission for approval to bring to market the WisdomTree CEF Fixed-Income Fund.

But read the ETF's prospectus. (You can find it here.) It actually involves a fund that would track an index of 75 closed-end bond funds that invest in taxable U.S. and international issues.

A CEF, of course, is a pooled investment vehicle that typically issues a limited amount of shares through an initial public offering. Sometimes, CEFs will issue more shares. But the idea is that new shares are limited and values are determined by a combination of underlying prices as well as the fund's overall net asset value, or NAV.

By contrast, open-end funds can issue as many shares on an ongoing basis as demand allows. Some investors like CEFs, since they can take advantage of periods when NAVs and underlying prices don't match. The situation creates valuation discount and premium swings during different market cycles.

"Through investment in these CEFs, the fund expects to have exposure to a wide range of fixed-income instruments such as: corporate bonds, government bonds, loan participations and mortgage-backed securities; as well as securities such as preferred stock that share many of the characteristics of traditional fixed-income instruments," the WisdomTree prospectus said.

Besides owning foreign bonds—both developed and emerging markets—the ETF would also include both investment-grade as well as high-yield issues.

No pricing details are included in the filings.