Why do two S&P 500 funds with the same holdings have different fees?

Because the expense ratio reflects the fund company's pricing, not the holdings — and identical index funds can charge wildly different fees. Every S&P 500 index fund owns essentially the same 500 stocks, so their pre-fee returns are nearly identical. The difference is what the provider keeps: one might charge 0.015% while another charges 0.50% or more for the very same exposure, often because the pricier fund is sold through commissioned channels or simply hasn't competed on cost. Over decades, that fee gap is the single biggest driver of the difference in what you actually pocket. The lesson is simple: when funds track the same index, choose the cheapest one — you give up nothing in return. Always check the expense ratio before buying, even for a "plain" index fund. See the long-run impact at wealthserene.com/tools/opportunity-cost.