Yet another flavor of exchange-traded funds just rolled off the assembly line, this one from

State Street Global Advisors

.

On Friday, the Boston-based money management shop started its own

streetTracks

family of exchange-traded funds, launching seven that trade on the

American Stock Exchange.

Unlike traditional open-end mutual funds that price at the end of each trading day, exchange-traded funds or ETFs are fixed baskets of several stocks, often tied to an index, that trade on an exchange as a single security. Because ETFs are cheaper and more convenient than traditional mutual funds, many believe they could start to replace mutual funds as the core holdings in many investors' portfolios.

State Street's list includes two ways to play the tech sector:

streetTracks Morgan Stanley High-Tech 35 Index

(MTK)

and

streetTracks Morgan Stanley Internet Index

(MII)

.

Another of the rookies,

streetTracks Dow Jones Global Titans Index

(DGT) - Get Report

, gives you access to the world's largest public companies. The other four essentially carve up the market by

market capitalization and valuation:

streetTracks Dow Jones Large Cap Growth Index

(ELG)

,

streetTracks Dow Jones Large Cap Value Index

(ELV)

,

streetTracks Dow Jones Small Cap Growth Index

(DSG)

,

streetTracks Dow Jones Small Cap Value Index

(DSV)

.

Like most ETFs, the fund's expense ratios are well below the average U.S. stock funds' 1.2% expense ratio.