Comparing the Two Largest ETFs: SPY vs. VOO

he Vanguard S&P 500 ETF has surpassed the SPDR S&P 500 ETF in size. What does this shift mean for individual investors?

Among passive exchange-traded funds (ETFs) tracking the S&P 500 index, State Street’s SPDR S&P 500 ETF Trust (SPY) has had the most assets under management (AUM) for the past 30 years.

In mid-February 2025, the Vanguard S&P 500 ETF (VOO) surpassed the SPDR S&P 500 in AUM. As of March 31, the Vanguard S&P 500 commands $590 billion, versus the SPDR S&P 500’s $576 billion.

What does this shift mean for individual investors? And, more importantly, does one fund deserve a place in your portfolio more than the other?