The State Street SPDR Portfolio S&P 400 Mid Cap ETF (SPMD) is an exchange-traded fund designed to closely mirror the overall investment performance of the S&P MidCap 400 Index, before accounting for its own fees and expenses. This cost-efficient ETF offers investors precise and extensive exposure to mid-sized U.S. companies. The underlying Index itself is constructed using a market capitalization weighting scheme, adjusted for the number of shares publicly available for trading (float-adjusted). SPMD is a component of State Street's economical SPDR Portfolio series, a collection of core investment vehicles crafted to provide broad and diversified access to essential asset classes, serving as fundamental building blocks for various investment portfolios.