Why SPYM Just Crossed $150 Billion While Most Investors Still Don’t Know It Exists

For a 28-year-old funding a Roth IRA at $7,000 a year, the choice between three S&P 500 ETFs comes down to a single basis point and a share price that fits a small contribution. The SPDR Portfolio S&P 500 ETF (NYSEARCA:SPYM) charges 0.02% annually and trades around $87 per share, which makes whole-share investing easier in a small Roth than Vanguard’s flagship, which trades at roughly $681 per share. SPYM, formerly trading under the SPLG ticker, was rebranded in 2025 as part of State Street’s portfolio ETF lineup.

The role this fund is built to fill

The SPDR Portfolio S&P 500 ETF exists to be a core U.S. large-cap holding at the lowest possible cost. It owns 508 individual securities drawn from the S&P 500, weighted by market cap, with a beta of 1.01. The top three positions are NVIDIA at 7.37%, Apple at 6.59%, and Microsoft at 4.38%, with information technology accounting for 37.76% of the portfolio.

The return engine is dividends from the underlying 500 companies plus price appreciation of the index. SPYM currently yields about 1.04% and is distributed quarterly, with the most recent payout of $0.2392 per share on the June ex-date. There are no options overlay, no leverage, and no factor tilt.

Where the math actually lands

The fee gap is one basis point: 0.02% on SPYM against 0.03% on VOO. Across 40 years of $7,000 annual contributions growing at 8% to a roughly $1.81 million ending balance, total fees come to about $360 versus $540. On a $500,000 balance held 30 years, the gap widens to roughly $15,000 to $25,000 in foregone growth.

Investor adoption has followed the cost story. SPYM crossed $100 billion in assets in 283 trading days after hitting $50 billion, took in over $32 billion in net inflows in 2025, and now sits at $150.38 billion in AUM.

Three constraints to weigh

1. Spreads are slightly wider. Bid-ask spreads run around $0.01 on SPYM versus near-zero on VOO. For frequent traders or large block orders, that friction can offset the expense ratio advantage.
2. Sector concentration mirrors the index. Tech sits at 37.76% of holdings, and the top 10 positions account for 35.91% of assets. A buyer of SPYM is buying mega-cap tech exposure, whether they want it concentrated or not.
3. Switching costs in taxable accounts. Selling existing VOO or iShares Core S&P 500 ETF (NYSEARCA:IVV) shares to capture one basis point would trigger capital gains taxes that erase the fee savings for years.

Who this fund fits

The SPDR Portfolio S&P 500 ETF fits a long-horizon saver building a core U.S. large-cap position in a tax-advantaged account where switching is free and small contributions must buy whole shares. For any investor already holding the Vanguard or iShares core trackers in taxable accounts, that 1-basis-point edge is simply not worth the tax bill. For an active trader cycling in and out frequently, the Vanguard fund’s tighter spreads matter more than the slight fee difference. Ultimately, the fund delivers on its promise: the S&P 500 at the lowest published expense ratio among major trackers, with a share price low enough to make a Roth contribution in whole units.

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