The Swiss Market Index (SMI) is Switzerland's blue-chip stock market index, which makes it the most followed in the country. It is made up of 20 of the largest and most liquid Swiss Performance Index (SPI) stocks. As a price index, the SMI is not adjusted for dividends.

The SMI was introduced on 30 June 1988 at a baseline value of 1,500 points. It closed above the symbolic level of 10,000 points for the first time on 2 July 2019. It reached the 12,000 point milestone on 17 June 2021. It is currently in a bear market, which it entered on 22 September 2022 after losing more than 20%. This ended the bull market that had reached an all-time record closing price short of 13,000 on 28 December 2021.

Its composition is examined once a year. As of September 2022, it contains 18 large-caps and two mid-caps. Calculation takes place in real-time. As soon as a new transaction occurs in a security contained in the SMI, an updated index level is calculated and displayed. However, the index is updated no more than once per second. The SMI is calculated in Swiss Francs, the currency of the Swiss Confederation.

The securities contained in the SMI currently represent approximately 70% of the free-float Swiss equity market capitalization, as well as 85% to 90% of the total trading turnover of Swiss and Liechtenstein equities listed on the SIX Swiss Exchange. Because the SMI is considered to be a mirror of the overall Swiss stock market, it is used as the benchmark for numerous mutual funds, index funds and ETFs, and as the underlying index for numerous derivative financial instruments such as options, futures and structured products.

In 2020, the SMI, along with other SIX indices, was endorsed under the EU Benchmarks Regulation and is registered with the European Securities and Markets Authority, which means that it can be used as an underlying for financial products sold in the EU.