Vanguard’s S&P 500 ETF has become the first exchange-traded fund to exceed $1 trillion in assets under management. The fund, which trades under the ticker VOO, drew $1.7 billion of net inflows in the latest trading day and more than $69 billion year to date, while the S&P 500 has gained 11% this year and repeatedly set record highs. The milestone underscores the expanding influence of passive investing, a strategy that tracks an index rather than relying on active stock selection, and points to its growing role in directing capital across equity markets. It also adds to concerns that the rise of trillion-dollar ETFs could heighten market stability risks and further challenge the viability of active management.