Assets held in exchange-traded funds reached $994.5 billion by the end of 2010, according to data compiled by the National Stock Exchange. That is up 27.1%, compared to a year earlier.

This compares to the $927.6 billion held in ETFS at the end of November, as reported on December 30 by the Investment Company Institute, the trade group. That compared to $923.5 billion at the end of October 2010 and $737.9 billion at the end of November 2009.

The NSX tally is a close mirror and a first glimpse of final year-end figures. For instance, NSX showed $782.2 billion in ETFs at the end of 2009; ICI put it at $771. billion.

Through 11 months of 2010, ICI had growth at 19.4%. The NSX figures show full-year growth of 27.1%

That is still down from 46.3% growth a year ago. But it's a big swing from 2008, when assets held in ETFs fell 13.5%, to $534.5 billion.

Clearly, though, investments in ETFs are slowing down. The ICI numbers showed that ETFs added $281.7 billion of investor money in the last 11 months of 2009 and only $150.5 billion in the first 11 months of 2010.

The biggest exchange-traded fund remains State Street's SPDR S&P 500, with $89.8 billion held.