All 20 largest ETF issuers posted net inflows in September; VOO lost $13.3bn

The 20 largest ETF issuers each took net inflows in September 2026, $150bn between them, according to Ultumus. iShares led the group with $58.3bn.

Vanguard’s S&P 500 ETF (VOO) lost $13.3bn net in September, the largest outflow among the world’s 20 biggest ETFs. Vanguard, the issuer, took in $27.8bn, which Ultumus described as Vanguard’s weakest month since March. VOO holds $1.03tn and is the only ETF in Ultumus’s coverage above the trillion-dollar mark.

The three largest issuers hold 65% of global ETF assets: iShares $6.41tn, Vanguard $5.13tn and SPDR $2.29tn. The same three took 69% of September’s top-20 inflows.

Global ETF assets ended September at $21.35tn, down 0.9% like-for-like as market moves subtracted 1.7 points against 0.8 points of net flows. Over the twelve months to September, assets grew 27.8% on the same basis, 15.7 points from flows and 12.1 from markets.

The other big S&P 500 ETFs all took money in September: SPY added $2.38bn, IVV $2.32bn and low-cost SPYM $3.39bn. Ultumus said SPYM has now had nine straight months of net inflows. Vanguard’s Total Stock Market ETF (VTI) added $5.90bn. Invesco’s QQQ lost $5.3bn, so the two largest outflows in the dataset came from broad index vehicles rather than niche ones.

Fixed income fund flows were mixed: iShares MBS ETF (MBB) lost $1.75bn and Vanguard Intermediate-Term Corporate Bond ETF (VCIT) $1.14bn. At issuer level, global fixed income stayed positive, with iShares taking $23.4bn and Vanguard $12.8bn.

For the twelve months to September, iShares took $648bn of net flows and Vanguard $642bn, a gap under 1%. Vanguard led in eight of those months; iShares owns the two biggest single months, $92.9bn in June and $87.9bn in December. September went to iShares.