The XLI is the ticker symbol for the Industrial Select Sector SPDR Fund, an exchange-traded fund (ETF) that focuses on the industrial sector of the U.S. stock market. It aims to provide investment results that correspond to the performance of the S&P 500 Industrial Sector Index, which includes companies involved in manufacturing, construction, and transportation. Investors use XLI to gain exposure to a diverse range of industrial companies without having to buy individual stocks. The fund includes major players in the industry, such as General Electric and Honeywell, making it a popular choice for those looking to invest in the industrial sector.