Those are "institutional investors," not "market makers." Market makers try their best to hold 0 shares. Note that some of Fidelity's shares, about 90% of Van

Those are "institutional investors," not "market makers." Market makers try their best to hold 0 shares. Note that some of Fidelity's shares, about 90% of Vanguard's shares, and 100% of BlackRock's [1] shares are held on behalf of index funds or index-linked ETFs. As passive holders, they do not trade on market news. [1]: Barclays Global Investors is actually owned by BlackRock, not by Barclays.