In another sign it hopes to make a big mark on the exchange-traded fund business, Pacific Investment Management Co. filed to launch six new ETFs Tuesday.

The move came the same day that Pimco's first ETF, a short-term Treasury fund, began trading among investors on NYSE Arca. One of the fastest-growing areas of the investment world, ETFs are baskets of stocks or bonds that trade throughout the day on an exchange.

The six newly proposed Pimco funds will cover longer-dated Treasurys and Treasury Inflation-Protected Securities, or TIPS, which resemble other Treasurys but adjust their principal to match changing prices. Pimco, owned by Allianz SE (AZ), earlier indicated it hopes to launch actively managed ETFs as well.

A large majority of the $72 billion in bond ETFs is in Barclays iShares funds. Several other firms have also launched Treasury and other types of bond ETFs hoping to loosen Barclays' grip on the business, without much success.

Apart from its well-regarded brand name, Pimco hopes to use its bond-market acumen to design funds that are easier than other ETFs for market makers to traffic in, potentially lowering costs for regular investors.

"We trade in the bond market every day throughout the day; it's a nuanced market," says Managing Director Tammie Arnold.

A preliminary prospectus for the six new funds was filed with Securities and Exchange Commission, dated June 2.

-By Ian Salisbury, Dow Jones Newswires; 201-938-5219; ian.salisbury@dowjones.com