SIL aims to track the equity market performance of global companies involved in the silver mining industry, including those engaged in silver mining and/or closely related activities such as exploration and refining. Constituents for the underlying index are derived from a ranking system based on their average daily trading volume in the last three months expressed in USD. Its portfolio is generally composed of 20-40 stocks and is also market-cap-weighted (subject to caps). The index is adjusted semi-annually.