Fidelity 500 Index Fund (FXAIX) is a mutual fund from Fidelity Investments (US) and State Street SPDR S&P 500 ETF Trust (SPY) is a ETF from State Street Investment Management. Over the past year FXAIX returned +18.19% while SPY returned +19.50%. Year to date, FXAIX is up 9.29% versus a gain of 9.93% for SPY.

Over three years, FXAIX compounded at +17.90% per year against +19.33% for SPY; over five years the annualized figures are +11.15% and +12.82% respectively. Across the full 5-year window we track, FXAIX has the edge at +11.15% annualized vs +8.74%. Past performance does not guarantee future results.

FXAIX has been the more volatile fund, with annualized monthly volatility of 15.7% compared with 15.3% for SPY. Lower volatility generally means a smoother ride, though it often comes with lower long-run returns.

The deepest peak-to-trough decline in our data was -25.4% for FXAIX and -56.5% for SPY. Drawdown depth is worth weighing if you expect to sell during market stress rather than ride it out.

The two funds' monthly returns correlate at 0.99. They move almost in lockstep, so holding both mostly duplicates the same exposure.

FXAIX charges 0.02% per year while SPY charges 0.09%. On a $10,000 position that is $2 vs $9 annually, a gap of $7 per year that compounds over a long holding period. On income, FXAIX currently yields 1.04% against 1.01% for SPY.