For the first time in three years, some new fixed-income exchange-traded funds are hitting the market.

Barclays Global Investors launched eight bond iShares on the New York Stock Exchange last week, bringing the total number available in the U.S. to 14. Barclays, a unit of Barclays Bank ( BCS) of the U.K, is the largest ETF provider in the U.S. and is the only one with bond funds on the market now, although others are believed to be planning new products.

Exchange-traded funds are baskets of securities that trade throughout the day on an exchange. While there are plenty of ETFs that track stock and even commodity indices, bond ETFs are harder to design because fixed-income securities trade over the counter, making it more difficult to obtain prices. Barclays' six other bond ETFs have total assets of around $20 billion, compared with $420 billion for the entire ETF market.

The eight new Barclays ETFs track bond indices designed by Lehman Brothers ( LEH). Three hold U.S. Treasury bonds: iShares Lehman Short Treasury Bond Fund ( SHV), iShares Lehman 3-7 Year Treasury Bond Fund ( IEI) and iShares Lehman 10-20 Year Treasury Bond Fund ( TLH).

The remaining five hold a mixture of U.S. Treasury bonds, sovereign bonds of other nations, agency debt and investment grade corporate debt: iShares Lehman 1-3 Year Credit Bond Fund ( CSJ), iShares Lehman Intermediate Credit Bond Fund ( CIU), iShares Lehman Credit Bond Fund ( CFT), iShares Lehman Intermediate Government/Credit Bond Fund ( GVI) and iShares Lehman Government/Credit Bond Fund ( GBF).

The expense ratios are 0.15% for the three Treasury funds and 0.20% for the five others.

Matthew Tucker, iShares' head of Fixed Income Investment Solutions, says the new ETFs expand the company's range of bond ETFs in terms of maturities and types of issuers. Barclays already has a full lineup of iShares equity products and is looking to provide a similar lineup of fixed-income products, he says.