NEW YORK ( TheStreet) - As evidenced by the monthly flow report from the National Stock Exchange, the ETF industry as a whole saw continued expansion in the final month of 2010, closing out the successful year on a strong note.

Notably, as investors continued to pile into these attractive products and the markets continued along the road to recovery total ETF/ETN assets managed to power through the $1 trillion mark.

From a sponsor perspective, BlackRock ( BLK) continues to be the largest fund provider, with assets under management totaling $447 billion. In 2010, $30 billion flowed into the firm's products. While the firm sits comfortably at the top of the list for now, in the coming year, investors will want to keep a close watch on Vanguard.

The $30 billion flowing into BlackRock's products marks a considerable decrease from the more than $40 billion that entered the company's products in 2009. Vanguard, on the other hand, saw an uptick in asset inflows from the year previous. In 2010, a total of $40 billion entered the company's products, beating the $28 billion which flowed into the firm's funds in 2009.

Much of Vanguard's rise to prominence in the ETF industry can be traced back to the company's ability to launch products which undercut the expense ratios of long standing veteran funds. At the end of 2010, Vanguard's total ETF assets under management stood at approximately $150 billion.

A number of smaller ETF providers saw staggering year-over-year inflow growth as they continued to find new and unique market niches to attract investors. Two themes which successfully drew investor assets over the past year were base- and precious metals- related funds.

Global X, which has recently taken to launching funds aimed at various metals producers, saw one of the largest upticks in inflows while relative newcomer, ETF Securities has continued to see a lot of success with its suite of physically-based precious metals funds.

Not all firms saw inflows over the past year, however. In 2010, U.S. Commodities Funds and Merrill Lynch's HOLDRs both saw investors head for the exits.

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