JHMM tracks the John Hancock Dimensional Mid Cap Index, which includes the 301st through 900th largest U.S. companies by market cap. Rather than weighting purely by size, the index adjusts positions based on three characteristics: smaller market cap within the mid-cap range, attractive price-to-book ratios, and strong operating profit margins. This generates a portfolio remarkably similar to traditional mid-cap indexes with subtle differences. The fund holds 94% of the same stocks as the Russell Midcap Index with just 31% active share, pursuing factors cautiously.