Legg Mason [LM] has begun the process of filing with the Securities and Exchange Commission to offer actively managed exchange-traded funds but has not yet decided what strategy the first offering will take. However, Legg Mason is looking at fixed income and equity strategies and is not planning on cloning any existing funds.

Assets in exchange-traded funds have grown 10 times over in the past decade, whereas mutual fund assets have doubled in that time, according to the Investment Company Institute. Last year, ETF assets rose 46% to $777.1 billion, and investors, still skittish about the market's 38% decline in 2008, withdrew $8.8 billion from stock mutual funds and a record $233.8 billion in 2008.