Pimco, the California-based investment giant, continues to dominate active ETF market share. But First Trust is nipping at its heels.

After co-founder Bill Gross' departure, Pimco continues to see outflow from its actively managed, fixed-income exchange traded funds. Investors pulled $312.8 million from Pimco products in November as its market share eroded by 4%.

First Trust attracted $1.08 billion in November inflow, up from roughly $600 million the previous month, according to the AdvisorShares' Active ETF Report released Dec. 10. The Illinois-based First Trust grew its market share by 5% and beat out 22 other active ETF sponsors in net flow for November.

Pimco had $6.65 billion in active ETF assets at the end of November, or 36% of the industry total. First Trust, with $3.3 billion, had 18%, according to the report.

As of Nov. 30, 122 actively managed ETFs were listed on U.S. exchanges. They included four new launches during the month. Assets grew by 5.7% to $18.39 billion. Still, that's a drop in the bucket of overall assets in the ETF industry: 1% of roughly $1.9 trillion.

At the end of 2013, there were 71 active ETFs holding $14.8 billion.

Short-term bonds continued to attract the most new investor dollars . At November's end, this asset class' 13 ETFs had 37% of actively managed market share.

Their popularity reflects the rising appeal of short-duration income funds over money-market funds that mostly pay nominal interest, about 0.01%, AdvisorShares CEO Noah Hamman told IBD. "Many advisers and investors are comfortable taking a small amount of risk to get a little more return."

Fast Start

Most of the short-term bond inflow went intoFirst Trust Enhanced Short Maturity ETF ( FTSM ). The fund has rapidly gained traction since its stock market debut on Aug. 5. Its assets almost tripled to $1.6 billion last month.

That growth made it the third-largest active ETF by asset size -- a remarkable jump from seventh in October and 98th in September.

Pimco Total Return ( BOND ) saw assets fall 4% to $2.45 billion in November, making it the second-largest active ETF. The top dog continued to bePimco Enhanced Short Duration ( MINT ), with $3.59 billion in assets, down 5% from October.

The top three active ETFs together held 42% of all assets in the space. MINT alone accounted for a fifth of the total. And most active ETF assets are in the fixed-income category.

Retail channels are spurring the growth in active ETFs, Hamman said, which is "different from when index ETFs first came out" and were mostly used by institutional investors.

AdvisorShares offers 26 active ETFs, more than any other sponsor. As the fourth-largest active ETF sponsor, it manages roughly $1.48 billion in assets.

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