The popularity of ETFs continues to surge this year. And investors definitely have a type they prefer.
Investors poured more than $138 billion into ETFs just in the month of September, says ETF.com. That was the biggest inflow for any month this year — and much of it flowed into big-cap U.S. stocks.
But most importantly, more than $930 billion in investors' asset flowed into ETFs this year. And that means 2025 is looking like another record year. Last year, a record $1.1 trillion flowed into ETFs. By year's end, ETF inflows could reach a record $1.35 trillion, says Matt Bartolini, global head of research strategists at State Street Investment Management.
"ETFs have become a go-to vehicle for investors seeking access to equity and fixed income markets," said Todd Rosenbluth of TMX VettaFi. "Both retail and institutional investors, including professional managers, are increasingly embracing them."
What Kinds Of ETFs Are Getting The Most Flows?
ETFs tied to the S&P 500 continue to win most assets. During September, the iShares Core S&P 500 ETF grabbed $18.9 billion in inflows, says ETF.com. That was the top winner in the month.
But other S&P 500 ETFs were on its heels. The Vanguard S&P 500 ETF, the largest ETF by assets, nabbed $4.4 billion in the month. And the iShares S&P 100 ETF, which owns only the most-valuable stocks in the S&P 500, pulled in $4.3 billion in the month.
And for the full year, both iShares Core S&P 500 and Vanguard S&P 500 are the most popular with investors. But investors are buying up other types of ETFs, too.
Bond ETFs Catch On
The popularity of ETFs isn't just for big-cap stocks. Bond ETFs are calling out to investors, too.
More than $39 billion flowed into bond ETFs in September, Bartolini says. For the year, iShares 0-3 Month Treasury Bond ETF lured $28.2 billion, ETF.com says. Vanguard Total Bond Market lured $13.9 billion for the year.
Bond ETFs are popular as investors look to add some stability to their portfolios. And for the same reason, both gold and bitcoin ETFs are proving popular. SPDR Gold Shares hauled in $4.2 billion in September alone. That brings its year-to-date tally to $15 billion.
Meanwhile, iShares Bitcoin Trust ETF continues to pull ahead of the pack of spot bitcoin ETFs. For the year, it pulled in $23.5 billion.
"Despite a strong stock market in 2025, ETF investors have also diversified into non-equity styles," Rosenbluth said. "Gold, bitcoin and fixed income ETFs have been in demand as they provide diversification benefits."
Some More Unusual Plays
The rise of ETFs has taken a bite out of mutual funds. And most of the money is flowing into index-based plays.
For the past month, though, some money is rolling into active ETFs that use human stock pickers or methodologies that try to beat the market. For instance, iShares AI Innovation and Tech Active ETF and iShares U.S. Equity Factor Rotation Active each gained roughly $3.3 billion in assets in September.
"Active ETFs have gathered nearly 40% of net inflows this year. Some investors are using them to seek higher returns, manage downside risk or generate elevated income, while others aim to replicate market performance," Rosenbluth said.
The question is: Can ETFs' popularity continue to rise? Likely, yes.
"I anticipated a slowdown in 2025 due to potential market volatility under a new administration. However, this proved incorrect," Rosenbluth said. "The momentum continues to favor ETFs, and with the pending launch of ETF share classes for mutual funds, flows into ETFs are likely to be even stronger in 2026."
Most Popular ETFs This Year
Funds luring the most assets this year so far, through September
| Name | Ticker | Net inflow year to date ($, billions) | Assets ($, billions) |
|---|---|---|---|
| Vanguard S&P 500 | VOO | $86.2 | $760.8 |
| iShares Core S&P 500 | IVV | 31.4 | 698.4 |
| iShares 0-3 Month Treasury Bond | SGOV | 28.2 | 57.9 |
| Vanguard Total Stock Market | VTI | 27.2 | 545.8 |
| iShares Bitcoin Trust | IBIT | 23.5 | 87.7 |
| SPDR Portfolio S&P 500 | SPLG | 23.1 | 86.5 |
| Invesco NASDAQ 100 | QQQM | 15.3 | 62.9 |
| SPDR Gold Shares | GLD | 15.0 | 124.6 |
| Vanguard Total Bond Market | BND | 13.9 | 139.3 |
| Vanguard Total International Stock | VXUS | 12.2 | 106.1 |
