How to Choose Between ITOT and SPTM for Total Stock Market Exposure
Introduction
If you’re building a long-term portfolio, total stock market ETFs offer a simple way to capture the entire U.S. equity landscape. Two popular options are the iShares Core S&P Total U.S. Stock Market ETF (ITOT) and the State Street SPDR Portfolio S&P 1500 Composite Stock Market ETF (SPTM). Both aim to provide broad coverage across large-, mid-, and small-cap companies, but subtle differences can influence which one fits your strategy. This step-by-step guide will walk you through the key factors to consider, helping you make an informed decision.
What You Need
- A brokerage account (any major online broker)
- Access to financial data platforms (e.g., Yahoo Finance, Morningstar, or your broker’s research tools)
- A clear understanding of your investment goals and time horizon
- Patience to compare metrics and do your due diligence
Step-by-Step Guide to Choosing Between ITOT and SPTM
Step 1: Understand the Underlying Indexes
Both ETFs track different but similar indexes, which drives their holdings. ITOT follows the S&P Total Market Index, which includes roughly 3,500 stocks representing the entire U.S. equity market. SPTM tracks the S&P 1500 Composite Index, a subset of the S&P Total Market Index that covers the 1,500 largest companies across large-, mid-, and small-cap segments. While SPTM’s index is a smaller slice, it still captures about 90% of U.S. market capitalization. The result is heavy overlap in their top holdings, with both funds concentrated in mega-cap stocks like Apple, Microsoft, and Amazon. However, ITOT includes thousands of additional micro-cap stocks, adding marginally more diversification at the fringes.
Step 2: Compare Expense Ratios and Costs
Expense ratios eat into returns over time, so lower is better. As of the latest data, both ETFs are extremely cost-effective: ITOT has an expense ratio of 0.03%, while SPTM charges 0.02%. That one basis point difference is negligible for most investors, but over decades, it can add up. For a $10,000 investment, ITOT costs $3 per year versus $2 for SPTM. While cost is a tie-breaker, it shouldn’t be the sole deciding factor given the tiny gap.
Step 3: Evaluate Performance and Risk Metrics
Key metrics to review include beta (volatility relative to the S&P 500), 1-year return, and dividend yield. The original data source notes that beta is calculated from five-year monthly returns, the 1-year return is trailing 12 months, and dividend yield is the trailing-12-month distribution yield. Since the indexes are highly correlated, ITOT and SPTM typically deliver nearly identical performance. For example, their 1-year returns often differ by less than 0.1%, and betas hover around 0.98–1.02, indicating similar volatility. Dividend yields also align closely. When comparing, use a reliable platform to pull the latest numbers—don’t rely on historical data alone, as yields fluctuate.
Step 4: Assess Portfolio Overlap and Diversification
Because both ETFs track S&P indexes with significant overlap, you don’t need to hold both—they’re interchangeable for most purposes. Check the percentage of common holdings using a tool like ETF Research Center or Morningstar’s X-Ray. Typically, ITOT and SPTM share 90%+ of their portfolio by weight. The main difference is that ITOT includes more micro-cap stocks, which can slightly increase diversification but also add a touch more risk. If you want the purest broad-market exposure, ITOT is your pick; if you prefer a leaner, more liquid portfolio of the largest 1,500 stocks, SPTM works fine.
Step 5: Check Trading Volume and Liquidity
Liquidity affects your ability to buy and sell without moving the price. ITOT trades about 2–3 million shares per day, while SPTM trades roughly 500,000 shares per day. Both are adequate for retail investors, but ITOT’s higher volume gives it a narrower bid-ask spread, reducing transaction costs for frequent traders. If you plan to dollar-cost average monthly, this difference is minor, but for large lump-sum purchases, ITOT may offer slightly better execution.
Step 6: Consider Tax Efficiency and Distributions
Both ETFs are structured as open-end index funds (not grantor trusts), so they are tax-efficient. They distribute qualified dividends, and neither has a history of large capital gains distributions. However, check the recent distribution history—if one fund has a slightly lower dividend yield, it may be slightly more tax-efficient in a taxable account. For tax-advantaged accounts (IRA, 401k), this is irrelevant.
Step 7: Make Your Decision Based on Your Goals
Ultimately, the choice comes down to personal preference. Use this checklist to finalize:
- If you want the broadest coverage (including micro-caps) → ITOT
- If you prefer the lowest expense ratio (by 1 bp) + slightly larger average market cap → SPTM
- If you need higher liquidity for active trading → ITOT
- If you’re adding other ETFs (like international or bonds), either works as a core holding
Remember that both funds are excellent choices—your portfolio’s overall allocation matters far more than picking between these two.
Tips and Final Considerations
- Don’t overthink it: Both ITOT and SPTM are among the cheapest and most efficient total market ETFs. The differences are marginal.
- Consider tax location: Place these ETFs in taxable accounts (they’re tax-efficient) or in tax-advantaged accounts depending on your overall strategy.
- Rebalance sparingly: Because they track similar indexes, you never need to rebalance between them. Hold one and stick with it.
- Watch for dividend reinvestment: Set up automatic dividend reinvestment (DRIP) to compound returns effortlessly.
- Stick to your plan: Avoid switching ETFs based on short-term performance; both will track the U.S. market almost identically.
By following these steps, you can confidently select the total stock market ETF that aligns with your investment philosophy. Happy investing!