The world’s biggest exchange-traded fund just got its biggest endorsement yet.
The $608 billion Vanguard S&P 500 ETF (ticker VOO) saw a nearly $21 billion inflow last month, the most in its 15-year history and the fifth largest amount ever taken in by a fund on a monthly basis, according to data compiled by Bloomberg Intelligence. It all happened as the underlying S&P 500 Index notched one of its choppiest months in recent memory, with large down days followed by relief rallies in the grip of President Donald Trump’s tariffs announcements.
Absorbing billions of dollars this year — to the tune of $55 billion — even amid intense market volatility helped VOO recently surpass the SPDR S&P 500 ETF Trust (SPY) in assets to become the largest ETF. VOO’s rock-bottom management fee of 0.03% has made it a hit, with retail traders in particular, and its ticker has become somewhat of a shorthand among market analysts for talking about flows from do-it-yourself investors.
SPY, on the other hand, charges 0.095% per year to track the same index. Despite a $2.2 billion inflow in April, State Street’s ETF has seen a net outflow of $27 billion so far in 2025, which, if the year were to end today, would mark its worst annual showing since 2015.
“The fact that VOO is seeing record flows in the face of a volatile market is a real testament to the amount of retail buying,” said Bloomberg Intelligence’s Athanasios Psarofagis. “In a month, Vanguard took in what many issuers have in total assets. It just shows how resilient Vanguard is during any market, and why it tends to grow faster in rougher markets than other issuers.”
The equities market was rocked last month by Trump’s tariff rollouts, which economists said would cause economic damage, dent consumer confidence and potentially lead to more intense inflation. Although the S&P 500 only ended up losing less than 1% for the month, day-to-day volatility reached historic levels amid the flip-flopping on levy policies. During April’s wild swings the Cboe Volatility Index, known as Wall Street’s fear gauge, closed at its highest level since 2020.
Money flowed into certain pockets of the ETF market anyway. VOO’s April haul constituted more than half of all equity ETF flows, which clocked in at over $33 billion, Bloomberg compiled-data show.
“Many investors are staying the course and adding to core holdings like VOO despite market volatility. Some of this is sticking with long-term strategies amid tariff noise, while another part is continued confidence in the strength of the US market,” said Roxanna Islam, head of sector and industry research at TMX VettaFi.
While VOO’s “gross activity” — or overall trading plus its derivatives universe — equals roughly a third of SPY’s, it often beat out the State Street vehicle last month when it comes to a list of the most traded funds by investors on the Interactive Brokers platform. To Steve Sosnick, it suggests that clients were putting money into longer-term investments.
“The popularity of VOO during April was a testament to individual investors’ continued faith in buying dips, and that they don’t only view downturns as short-term trading opportunities,” said Sosnick, Interactive Brokers’ chief strategist.
