The economy may be going through a rocky period, but the S&P 500 was sitting pretty in terms of indexed assets at the end of 2007. Standard & Poor's just released its annual report on assets tied to its indexes, and the numbers are pretty interesting.

First of all, a whopping $4.85 trillion is benchmarked to the S&P 500 (a figure that includes actively managed funds), which isn't too surprising. After all, most funds with any significant domestic large-cap holdings seem to use the iconic index as a benchmark.

But $1.47 trillion, or about 30%, of that is indexed assets, a 12% increase in assets from the end of 2006 and almost a 100% increase from the end of 1997. Meanwhile, the S&P 500 was up 5.49% for 2007.

Keep in mind, however, that the $1.47 trillion includes not just S&P 500 index funds, but also enhanced index assets and assets tied to style and composite indexes that are derived from or include the S&P 500. "Only" about $1.2 trillion of that is in regular index funds or exchange-traded funds.

The grand total of indexed assets for all of S&P's indexes is $1.71 trillion, meaning the S&P 500 represents about 86% of that. After the S&P 500, the S&P MidCap 400 Index has about $67.7 billion in assets indexed to it, while the S&P SmallCap 600 has about $33.3 billion in indexed assets. The S&P MidCap 400 and S&P SmallCap 600 both saw the amount of assets tied to them decrease - by 4% and 9%, respectively. International indexes only had about $107 billion tied to them.

About $209 billion of the total assets were in ETFs (with $150 billion of that invested in the S&P 500 Index alone), while the rest was in enhanced and traditional index mutual funds.

You can access the "Annual Survey of Indexed Assets" here.