Small-Cap ETF Investing: ISCB vs. SPSM

State Street SPDR Portfolio S&P 600 Small Cap ETF (NYSEMKT:SPSM) and iShares Morningstar Small-Cap ETF (NYSEMKT:ISCB) both target U.S. small-cap stocks, but ISCB offers broader diversification and has outpaced SPSM over the past year, albeit with slightly higher costs.

Both SPSM and ISCB aim to give investors exposure to U.S. small-cap equities, but they differ in how they construct their portfolios and in some important metrics. This comparison digs into cost, performance, risk, holdings, and trading considerations to help clarify which ETF may appeal more, depending on investor priorities.

Snapshot (cost & size)

Beta measures price volatility relative to the S&P 500; beta is calculated from five-year monthly returns. The 1-yr return represents total return over the trailing 12 months.

ISCB comes with a marginally higher expense ratio than SPSM, making SPSM slightly more affordable. SPSM also has a modest edge in dividend yield, which may appeal to investors seeking a higher payout from their small-cap allocation.

Performance & risk comparison

What's inside

ISCB tracks a broad set of U.S. small-cap stocks, holding 1,561 companies as of March 11, 2026. The fund tilts slightly toward industrials (20%), financial services (17%), and healthcare (14%). Its top holdings include Lumentum Holdings, CF Industries, ATI, and Albemarle, though none represent more than 1% of assets, highlighting the fund’s diversification.

In contrast, SPSM focuses on the S&P SmallCap 600 index, which results in a portfolio of 603 holdings. It is slightly heavier in financial services (18%), with comparable weightings in industrials. Top names like Solstice Adv Materials, Interdigital, and CareTrust REIT each comprise less than 1% of the fund. Neither fund employs leverage or carries notable quirks, but SPSM’s more concentrated approach may lead to different sector exposures over time.

For more guidance on ETF investing, check out the full guide at this link.

What this means for investors

Investing in small-cap stocks provides an opportunity to capitalize on greater upside potential as these businesses grow. It can also be a good way to diversify a portfolio that already holds traditional large-cap stocks that may offer stability but slower growth. And investing via an exchange-traded fund means you don’t have to worry about backing the right small-cap stock — instead, you can focus on which small-cap investing strategy fits your style best.

The matchup between ISCB and SPSM is a good example of this. SPSM is an index fund that seeks to track the S&P SmallCap 600 index. That means its holdings will always be limited to around 600 stocks that also comprise that index. To be included in the index, a stock must have a market cap between $1.2 billion and $8 billion and companies must have positive earnings over the most recent quarter as well as cumulatively over the most recent four quarters.

ISCB holds more than twice as many stocks, but its total assets under management is just a fraction of SPSM’s. It tracks the Morningstar US Small Cap Extended Index, which has slightly different criteria for inclusion. One big difference is that there is no profitability requirement for inclusion in the Morningstar index. The two ETFs have performed pretty similarly over the last one and five years, offer similar dividend yields, and charge similar expense ratios. Choosing between the two will likely come down to which index criteria you prefer.

Sarah Sidlow has no position in any of the stocks mentioned. The Motley Fool has positions in and recommends Lumentum. The Motley Fool has a disclosure policy.