The S&P 600 Index

The S&P SmallCap 600 Index, often referred to as the S&P 600, is a stock market index that tracks the performance of 600 small-capitalization publicly traded companies in the United States. It is maintained by S&P Dow Jones Indices.

S&P SmallCap 600 component stocks

Here are some key characteristics of the S&P 600:

• Focus on Small-Cap Companies: Unlike the S&P 500 (large-cap) and S&P 400 (mid-cap), the S&P 600 specifically targets companies with small market capitalization. This segment of the market is often associated with higher growth potential but also greater volatility.
• Market Capitalization Weighting: The index is weighted by free-float market capitalization, meaning companies with larger market values have a greater influence on its performance.
• Representation of the Small-Cap Segment: It is considered a key benchmark for the U.S. small-cap equity market, reflecting its unique risk and return characteristics.
• Component of the S&P Composite 1500: The S&P 600 is one of the three indices (along with the S&P 500 and S&P 400) that make up the S&P Composite 1500, providing a comprehensive view of the U.S. equity market across different size segments.
• Selection Criteria: Companies are included based on specific criteria, including market capitalization, liquidity, and financial viability. To be eligible, companies typically need to have a market capitalization within a certain range, which is distinct from the mid-cap and large-cap indices to avoid overlap. The market cap range for inclusion is periodically reviewed and adjusted.
• Number of Constituents: While named the S&P 600, the index sometimes comprises slightly more than 600 stocks due to companies having multiple share classes.

Performance:

As of September 12, 2025, the S&P 600 Index closed at 1,441.84.

The S&P 600 offers investors exposure to the smallest companies within the U.S. equity market, which can provide diversification and growth opportunities, though it comes with higher risk compared to larger-cap indices.