S&P 400
| Foundation | June 19, 1991 | 
|---|---|
| Operator | S&P Dow Jones Indices | 
| Exchanges | |
| Trading symbol | 
 | 
| Constituents | 401 | 
| Type | Mid-cap | 
| Market cap | US$3.1 trillion (as of December 31, 2024) | 
| Weighting method | Free-float capitalization-weighted | 
| Related indices | List | 
| Website | spglobal.com/sp-400 | 
The S&P MidCap 400 Index, more commonly known as the S&P 400, is a stock market index from S&P Dow Jones Indices.