Yahoo Finance analysis indicates that S&P 500 index funds such as Vanguard S&P 500 ETF (VOO) and SPDR S&P 500 ETF (SPY) face concentration risk. As of July 31, 2026, the top ten holdings accounted for 38% of the funds' total value, with the top three holdings making up 20%. The article suggests that investors could consider equal-weight funds like Invesco S&P 500 Equal Weight ETF (RSP) as an alternative to diversify risk.