Not true for Vanguard. Index funds that are not 'actively' managed are not required to purchase ALL stocks in their index. Vanguard funds are a sampling of the index according to their prospectushttps://investor.vanguard.com/investment-products/etfs/profile/vti. This would indicate that Vanguard is performing due diligence and research when selecting which stocks and how much of each stock to add to their index funds.
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