VTI tracks the CRSP US Total Market Index. ITOT, run by BlackRock's iShares, follows the S&P Total Market Index (TMI). Both reach across mega caps, mid caps, and small caps, so the top of each portfolio looks nearly identical. ITOT's published top holdings include NVIDIA at 6.69%, Apple at 5.88%, Microsoft at 4.34%, Amazon at 3.21%, and Alphabet's Class A shares at 2.64%.