The Barclays Global Investors iShares exchange-traded fund group plans to launch an ETF tracking mortgage-backed securities, a spokeswoman said on Wednesday.

The iShares Lehman Mortgage Backed Securities Fund will begin trading on the American Stock Exchange on or around Friday with the ticker MBB.A.

According to Financial Research Corp., a Boston-based firm, BGI had net inflows of $44.5 billion last year, second in the U.S. fund business to American Funds, which took in a net $74.0 billion.

The iShares ETFs ended 2006 with nearly $300 billion of assets, making Barclays by far the largest ETF player.

Net inflows into the iShares ETF group so far this year are tracking closely with the last three years, when the annual pace was roughly $45 billion to $50 billion, iShares Chief Executive Lee Kranefuss said in an interview on Wednesday.

"The ETF market as a whole continues to grow at a very good clip," Kranefuss told Reuters.

A recent study by Morgan Stanley projected that global ETF assets will grow to $2 trillion by 2011.