S&P 600

The S&P SmallCap 600 Index (S&P 600) is a stock market index established by S&P Global Ratings. It covers roughly the small-cap range of American stocks, using a capitalization-weighted index.

To be included in the index, a stock must have a total market capitalization that ranges from $1.2 billion to $8 billion.^[4] These market cap eligibility criteria are for addition to an index, not for continued membership. As a result, an index constituent that appears to violate criteria for addition to that index is not removed unless ongoing conditions warrant an index change.^[4]

Additionally, same as S&P 500 and S&P 400, there is a financial viability requirement. Companies must have positive as-reported earnings over the most recent quarter, as well as over the most recent four quarters (summed together).

As of 30 January 2026^[update], the index's median market cap was $2.25 billion and covered less than three percent of the total US stock market capitalization. These smallcap stocks cover a narrower range of capitalization than the companies covered by the Russell 2000 Smallcap index, which range from $169 million to $4 billion,^[5] excluding some of the smallest companies. The S&P 400 MidCap index combined with the SmallCap 600 compose the S&P 1000, and the S&P 1000 plus the S&P 500 compose the S&P 1500. The index was launched on October 28, 1994^[6] and its ticker symbols are either SML, ^SML, SP600 or ^SP600 depending on the financial website.