SPYM leads IWF by 9.4 percentage points in 2026. They are not the same bet

Through the close on Oct. 20, State Street SPDR Portfolio S&P 500 ETF SPYM was up 12.85% on price in 2026. BlackRock's iShares Russell 1000 Growth ETF IWF was up 3.45%. Dividends are not in those figures, and the gap is 9.4 percentage points.

The gap belongs to the indexes, not the managers. Over the same stretch the S&P 500 was up 12.67%, and SPYM stayed with it, while the Russell 1000 Growth index was up 3.45%, the same figure as IWF.

A market fund and a growth fund

SPYM seeks the S&P 500's total return before fees and expenses, and State Street lists the expense ratio at 0.02%. IWF seeks the Russell 1000 Growth index, and BlackRock's July 31, 2026 summary prospectus lists the expense ratio at 0.18%.

The fee difference is 0.16 percentage points, $16 a year on $10,000. In the latest issuer reports both funds are huge, $182.9 billion in SPYM and $124.6 billion in IWF, and each trades at a penny-wide 0.01% median bid-ask spread over 30 days.

FTSE Russell, which owns the growth index, fills it with large U.S. companies that have higher price-to-book ratios, higher forecast growth and faster historical sales growth, so IWF is a style screen rather than the market.

Shared stocks, held differently

The two portfolios overlap by 57.8% by weight, the portion of the two books that is identical once each shared stock is counted at the smaller of the two weights. They share 179 names.

Technology was 54.75% of IWF as of Oct. 15 and 37.82% of SPYM as of Oct. 16. In those holdings, communication services was 16.91% of the growth fund and 9.71% of the market fund, while financials were 11.84% of SPYM and 4.93% of IWF.

The growth fund is the more concentrated of the two. The ten largest companies were 60.4% of IWF and 40.2% of SPYM, and Nvidia, the largest holding in both, was 15.2% of the growth fund and 7.9% of the market fund.

As of Sept. 30, the 30-day SEC yield was 1.04% for SPYM and 0.28% for IWF.

The longer record does not all point one way

For the 12 months ended Sept. 30, with distributions reinvested, State Street reported 15.70% for SPYM against 15.74% for the S&P 500, and BlackRock reported 7.29% for IWF against 7.50% for the Russell 1000 Growth index. Each fund tracked its index: SPYM trailed by 0.04 percentage point, and IWF trailed by 0.21 percentage point.

These are annualized total returns through Sept. 30, from FTSE Russell for the growth index and from State Street for the S&P 500.

Growth led over three years, and over ten years it led by 2.8 percentage points a year. Over five years the S&P 500 was ahead by 0.13 percentage point a year.

SPYM's own ten-year record is not the comparison to use, because its benchmark was other large-cap indexes until Jan. 24, 2020. The index figures match the two strategies as they stand.

Own the market, or add a smaller sleeve

If this is your U.S. stock holding, own SPYM. You get the market at 0.02%, and in 2026 you got the market's result. IWF on its own is a growth screen that has trailed that result by 9.4 percentage points, so switch if that was not the bet you meant.

If you already own the market and want more growth, add IWF as a small sleeve on top of SPYM, and keep the market fund as the larger holding. A tilt is that smaller extra, an amount you could sell without the portfolio becoming a different bet. Half the account is not a tilt.

You pay nine times the fee for a fund that is more than half technology. The sleeve trailed in 2026, led over the past decade, and was a wash over five years.

Do not split the money evenly and call it balance. The portfolios already overlap by 57.8% by weight, and IWF holds the shared stocks heavier, so the second fund is a second helping of the same giants.