ZXLB invests in basic materials companies from the S&P 500, these would include companies in the chemicals, metals and mining, paper and forest products, containers and packaging, and construction materials industry. Its S&P 500-only portfolio means that it favors large-caps. To achieve its investment objective, the fund may invest directly in the index constituents securities or hold other securities with similar investment profiles through a sampling strategy. It may also use derivatives, enter securities lending and repurchase agreements, and engage in short selling to maximize its returns. The constituents are market cap-weighted with quarterly index rebalancing.