iShares Global 100 ETF (IOO)

IOO seeks to deliver cap-weighted exposure to 100 of the world's largest multinational companies from its parent index, the S&P Global 1200, and lands squarely in the mega-cap rather than the large-cap domain. The fund avoids midcaps altogether. Its focus on mega-caps, and its avoidance of emerging markets outside Korea, introduces some sector and geographic tilts. The index measures the performance of blue-chip companies of major importance that have global exposure. For companies to be considered global in nature, they must derive a substantial portion of revenue and assets from multiple countries. The index is rebalanced quarterly starting every March.