Pimco, the world's largest bond fund manager in terms of assets, is set to launch two new Treasury-linked exchange-traded funds.

Pimco 20+ Year Zero Coupon U.S. Treasury Index Fund (NYSEArca: ZROZ) was listed Friday but hasn't launched. The fund will track the BofA Merrill Lynch Long Treasury Principal STRIPS Index.

Net annual operating expenses are pegged at 0.15 percent.

The company will also be launching a midmaturity fixed-income fund: the Pimco 3-7 Year U.S. Treasury Index Fund (NYSEArca: FIVZ). It will track the Merrill Lynch 3-7 Year U.S. Treasury Index.

It, too, will charge 0.15 percent in expenses.

You can read Pimco's prospectuses here and here.

The launches add new players to a growing space for bond funds. Among competitors in that space, ZROZ will face the Vanguard Extended Duration Treasury ETF (NYSEArca: EDV), which was launched in December 2007 and tracks the Treasury STRIPS 20-25 Year Equal Par Bond Index. The fund has some $252.5 million in total assets and expenses of 0.14 percent. EDV has a yield of 4.26 percent.

Meanwhile, in the intermediate maturity space, FIVZ will face iShares Barclays 3-7 Year Treasury Bond Fund (NYSEArca: IEI), which lists total assets at $842.9 million and a yield of 2.58 percent. IEI's expenses are pegged at 0.15 percent.

This story initially said that Pimco would launch the funds on Thursday, Oct. 22. But the company has now postponed that launch to an undisclosed later date.