The Swiss Performance Index is a wide total-return index that tracks equity primarily listed on SIX Swiss Exchange with a free-float of at least 20%, and excluding investment companies. The index covers large, mid and small caps and is weighted by market capitalization. Most constituents, although not all, are domiciled in Switzerland or the Principality of Liechtenstein. The SPI is Switzerland's most closely followed performance index. It is used as a benchmark for mutual funds, index funds and ETFs, and as an underlying index for derivative financial instruments such as options, futures and structured products. In 2020, the SPI, 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. Wikipedia