SMI, SPI, SMIM and Co.: Which Stock Indices Are There on the Swiss Stock Exchange?

An equity index is a kind of market mood barometer: It collates selected equities into a single value and shows how a certain market segment evolves. You can compare it to a fruit basket. Instead of watching each individual equity, the index provides an overall view at a glance. The more equities there are in the basket, the more diversified the risk.

SIX maintains an entire family of indices. Here are the most important ones at a glance:

The Swiss Market Index (SMI) is the best-known Swiss equities index. It includes the 20 largest and most liquid companies, which account for roughly 75% of the overall market capitalization of the Swiss equities market. Individual securities are weighted at a maximum of 18%, ensuring that no two companies combined account for more than 20%. As a pure price index, the SMI does not take dividends into account. This is an important difference from the SPI.

The Swiss Performance Index (SPI) is considered the comprehensive benchmark of the Swiss equities market. With more than 200 companies from Switzerland and Liechtenstein, it represents almost the entirety of the market listed on the SIX Swiss Exchange. In contrast to the SMI, the SPI is a performance index: Dividends are taken into account. Those wishing to measure the long-term overall return of the market therefore look at the SPI.

The SMI Mid (SMIM) focuses on the 30 largest companies that aren’t represented on the SMI. It gives access to mid-sized companies with high growth potential, and often reacts differently to market fluctuations than the SMI – for example, it reacts more sharply to developments in the Swiss domestic economy.

The Swiss Leader Index (SLI) combines the 20 SMI securities with the 10 largest companies from the SMIM. Its distinctive feature: The four largest positions are each limited to 9%, while all others are capped at 4.5%. This significantly reduces concentration risk and makes the SLI especially attractive to institutional investors.

For those looking to combine the best from the SMI and SMIM, the SMI Expanded is the answer. It includes the 50 largest and most liquid Swiss equities. The SPI Extra goes in a different direction: It contains all SPI companies that are not included in the SMI, i.e., Small- and Mid-Caps. This makes it particularly relevant as a benchmark for portfolio managers who invest outside of the heavyweights.

The most comprehensive index is the Swiss All Share Index. It includes all Swiss and Liechtensteiner equities listed on the SIX Swiss Exchange, as well as those with a free float below 20%, which are not incorporated in the SPI.

There’s one detail that many overlook: Not every index is calculated the same way. Price indices such as the SMI only take into account price development of the equities they contain. Dividends aren’t taken into account. In contrast, performance and total return indices such as the SPI take dividend disbursement into account, in most cases with the expectation that they will be immediately reinvested. Over many years this results in a noticeable difference in the reported return.

Many index families are also available in both variants. In addition to the classic SMI there is the SMI TR (SMI Total Return), with the same 20 equities, but including dividends. When comparing two indices, or a single index across multiple years, one should always check to see if the same calculation basis is being used: Price with price values, and performance with performance values.

Admission into an index follows clear rules: The decisive factors are free-float market capitalization and trading volume. A company must have a free float of at least 20%. This means that at least a fifth of its shares must be readily available for the public to buy or sell and must not be held by major shareholders or in the hands of the founders on a permanent basis. Only then can a company be admitted to the SPI. The composition of most indices is reviewed annually in September. In the wake of unusual events such as takeovers or mergers, extraordinary adjustments can occur outside of the regular review schedule. 

Not entirely. Since many companies are represented in multiple indices simultaneously, major movements in the SMI often spill over to the SPI or SLI. Nestlé, Roche, and Novartis, for example, are in both the SMI and the SPI.

However, the indices react with differing degrees of intensity. Historically, the SMI is heavily influenced by these three heavyweights. If one of these stocks falls significantly, it pulls the SMI downward sharply. The SLI can better dampen such movements due to its more balanced weighting. Mid-Cap indices such as the SMIM often exhibit a slight delay, and their own dynamic. They react more strongly to the Swiss domestic economy while the globally active SMI companies react more quickly to international events, for example to the Fed increasing the prime rate.

At the beginning of April 2026, SIX launched two new indices, thus expanding the existing range on offer.

The SMI Equal Weighted includes the same 20 companies as the SMI. But this index doesn’t weight them by market capitalization, instead weighting them equally at 5% each. Rebalancing is done quarterly. The aim is to lower the concentration risk associated with individual heavyweights and to represent the blue-chip segment in a more balanced way. This is particularly interesting to more risk-conscious investors who still wish to remain within the familiar SMI universe.

The SPI ESG 25 selects 25 companies according to market capitalization, trading volume, and ESG rating via the independent Swiss rating company Inrate. The four largest positions are capped at 9%, while all others are capped at 4.5%. 

Indices themselves cannot be bought directly. Investors invest via financial products such as ETFs, index funds, or structured products that track a specific index. The index that serves as the basis for this depends on the investor’s strategy:

• Broader market, easier access: SPI or SMI as ETF
• Reduced concentration risk: SLI or the new SMI Equal Weighted
• Growth potential through mid-caps: SMIM or SPI Extra
• Sustainable investing: SPI ESG 25
• Complete market coverage: Swiss All Share Index