The MSCI All Country World Index (ACWI) is a stock index designed to track broad global equity-market performance. Maintained by Morgan Stanley Capital International (MSCI), the index comprises the stocks of nearly 3,000 companies from 23 developed countries and 25 emerging markets.The ACWI is a popular choice for investors seeking to diversify their portfolios across international markets. While the index includes companies from both developed and emerging economies, its focus on large cap stocks means that it may not provide as much exposure to small cap or mid cap stocks as some other global indices. Nevertheless, the ACWI remains an important benchmark for those looking to invest in international equities.