Analysis shows that the Vanguard S&P 500 ETF (VOO) and Invesco NASDAQ 100 ETF (QQQM) have a 53% overlap in holdings. Both ETFs are heavily concentrated in the tech sector, with VOO holding about 36% of its assets in tech and QQQM holding roughly 66% in tech. Seven stocks, including Nvidia, Apple, and Microsoft, are in the top 10 of both funds, accounting for about 33% of the S&P 500 and 34% of the Nasdaq-100. Combining them makes a bigger bet on a single sector, increasing concentration risk.