The Index is designed to measure the performance of information technology companies included in the S&P 500 Index. The S&P 500 Index is designed to measure the performance of the largest 500 companies listed and domiciled in the U.S. The Index includes information technology companies in the following industries according to the Global Industry Classification Standard (GICS) as IT services, software, communications equipment, technology, hardware, storage and peripherals, electronic equipment, instruments, and components, and semiconductors and semiconductor equipment. These companies are then weighted based on market capitalization. The Indexs composition and the assigned weights are reevaluated every September with additional weight adjustments in March, June, and December.