Exchange-traded funds grew their assets by $88 billion in January, an amount that far exceeded the industry's $51 billion increase in assets for all of 2011, according to the ETF Industry Association.

All told, ETF held assets of $1.134 trillion at the end of last month in 1,189 products.

A large chunk of January's growth came from price appreciation in the underlying assets, particularly on the equity side which comprises roughly 70% of total ETF assets. On a strictly price basis, the S&P 500 index gained 4.4% in January. That matched the gain on the S&P Europe 350 index, while various S&P indexes for global markets (ex. U.S.), Asia and Latin America leaped in a range between 7.1% to 10.3%.

That said, net cash flows into ETFs during the month were $28 billion, which topped the $16 billion that flowed into ETFs in December 2011 and more than tripled the monthly inflows in the year-earlier period.

"Obviously, the year got off to a good start," says Tom Graves, equity analyst at S&P Capital IQ, a provider of market data and research. "But it's part of a long-term trend of ETFs gaining larger market share relative to traditional mutual funds and individual securities."

The ETF Industry Association found the top three providers dominated the industry, led by BlackRock (43%) and followed by State Street (25%) and Vanguard (17%). But Graves notes that newer ETF providers are making inroads thanks to innovative products, stronger distribution and/or lower costs.

According to S&P Capital IQ, 12 of the 20 largest ETFs have an equity emphasis, while seven are focused on fixed income and the remaining fund is commodity-oriented.

Fixed-income funds saw net inflows of $7.4 billion in January, or about one-quarter of total ETF inflows for the month. That amount was 164% greater than the year-earlier period.