Total Market Fund vs S&P 500: A Comprehensive Comparison
Robert Stowe, AAMS® | Investment Advisor
Two indices dominate passive U.S. equity investing: the S&P 500, tracking 500 large-cap companies representing roughly 80% of U.S. market capitalization, and the CRSP U.S. Total Market Index, capturing nearly 100% of the investable market across approximately 4,000 stocks. Despite vastly different composition, these indices deliver remarkably similar long-term returns, with a correlation of 0.99, raising a fundamental question: does the additional diversification of a total market approach actually matter?
Index Fundamentals
Understanding how each index is constructed reveals why they behave so similarly despite different approaches. Both use free-float market capitalization weighting, meaning larger companies have proportionally greater influence on index returns. This shared methodology explains much of their correlation.
S&P 500 Index
Holdings: ~500 large-cap U.S. companies
Market Coverage: ~80% of U.S. equity market capitalization
Selection Method: Committee-based with financial viability requirements
Weighting: Free-float market capitalization
Reconstitution: Quarterly (committee discretion)
Inception: 1957 (90-stock precursor since 1926)
CRSP U.S. Total Market Index
Holdings: ~4,000 constituents across all market caps
Market Coverage: ~100% of U.S. investable equity market
Selection Method: Rules-based (no committee discretion)
Weighting: Free-float market capitalization
Reconstitution: Quarterly (rules-based)
Inception: April 2011 (data available from December 2012)
Key Structural Differences
The fundamental distinction lies in what each index excludes. The S&P 500 deliberately screens for large, financially viable companies through a committee selection process, while the CRSP Total Market Index uses objective rules to capture every investable U.S. stock regardless of size or profitability.
| Feature | S&P 500 | CRSP Total Market |
|---|---|---|
| Selection Method | Committee-based | Rules-based |
| Constituent Count | Fixed (~500) | Flexible (~4,000) |
| Small/Micro Cap Exposure | None | ~8-13% of holdings weight |
| Financial Viability Requirement | Yes | No |
| Coverage Philosophy | Representative | Comprehensive |
What's in CRSP Total Market But NOT in S&P 500?
The CRSP Total Market Index includes approximately 3,500 additional companies beyond the S&P 500. These consist primarily of small-cap stocks (2,000+ companies), micro-cap stocks (the smallest publicly traded U.S. companies), recently IPO'd companies (included after 5-20 trading days versus S&P 500's longer review period), and companies that don't meet S&P 500's market cap threshold ($22.7B+), liquidity requirements, or financial viability criteria.
However, because of market-cap weighting, these ~3,500 additional stocks comprise only about 13% of the total market index weight. The S&P 500 stocks still represent approximately 87% of the CRSP Total Market Index by market cap.
Sector Breakdown Comparison
Because both indices use market-cap weighting and share the same largest holdings, sector allocations are remarkably similar. The CRSP Total Market Index shows marginally less concentration in technology and communication services due to the dilution effect of small and mid-cap companies, which tend to be more heavily represented in industrials, financials, and consumer discretionary sectors.
| Sector | S&P 500 Weight | Est. CRSP Total Market Weight | Variance |
|---|---|---|---|
| Information Technology | 34.6% | ~32-34% | Slightly lower |
| Financials | 13.1% | ~11-13% | Similar to slightly higher |
| Communication Services | 10.7% | ~9-10% | Slightly lower |
| Consumer Discretionary | 10.3% | ~12-14% | Slightly higher |
| Health Care | 9.8% | ~11-12% | Similar |
| Industrials | 8.0% | ~11-13% | Higher (more small-cap) |
| Consumer Staples | 4.9% | ~5-6% | Similar |
| Energy | 2.8% | ~4-5% | Slightly higher |
| Utilities | 2.4% | ~2-3% | Similar |
| Real Estate | 1.9% | ~2-3% | Slightly higher |
| Materials | 1.7% | ~2-3% | Slightly higher |
Note: Sector weightings change frequently as market values fluctuate. The S&P 500 percentages shown are approximate and subject to change. Verify current sector allocations on fund provider websites.
Concentration Analysis
Both indices exhibit significant concentration in their top holdings. In the S&P 500, the top 10 companies represent approximately 38% of index weight, with the "Magnificent Seven" tech stocks alone comprising over 30%. The top three sectors (Information Technology, Financials, Communication Services) represent roughly 58% of the index.
The CRSP Total Market Index shows marginally less concentration. The top three sectors represent approximately 55-57% of the index because small and mid-cap exposure provides slight dilution. However, because the index is market-cap weighted, large-cap stocks still drive the majority of total market returns, demonstrating how thoroughly large-caps dominate both approaches.
Performance Comparison
Historical returns reveal a surprising truth: despite the S&P 500 holding only 500 stocks versus the total market's 4,000, long-term performance differences are negligible. This happens because market-cap weighting causes large stocks to dominate returns in both indices.
| Time Period | S&P 500 (VOO) | CRSP Total Market (VTI) | Typical Pattern |
|---|---|---|---|
| 3-Year Annualized | ~10-11% | ~10% | Slight S&P 500 edge in large-cap-led periods |
| 5-Year Annualized | ~14-15% | ~14% | Similar |
| 10-Year Annualized | ~14-15% | ~14-15% | Similar, slight S&P 500 edge in recent decade |
| Since 1957 (Annualized) | ~10.00% | ~10.03% | Virtually identical |
Note: Performance figures are approximate historical averages and will vary based on the specific period measured. Verify current returns on fund provider websites. Past performance does not guarantee future results.
Understanding the Performance Pattern
Over the past decade, the S&P 500 has held a slight edge because large-cap growth stocks, particularly technology companies, dominated market returns. When large-caps lead, the S&P 500 benefits from higher concentration in those winners. Conversely, during periods of small-cap outperformance (such as 2000-2009), the total market index gains an advantage from its broader exposure.
The critical insight: over extended periods (65+ years), this difference virtually disappears. The CRSP Total Market Index has outperformed by approximately 0.03% annually since 1957, a difference that is statistically negligible and could easily reverse over the next 65 years.
Rolling Period Performance Patterns
| Market Condition | Typical Leader |
|---|---|
| Large-Cap Dominance (2010s-2020s) | S&P 500 |
| Small-Cap Rallies | CRSP Total Market |
| Risk-Off Periods | S&P 500 |
| Early Economic Recoveries | CRSP Total Market |
Correlation & Risk Analysis
The extremely high correlation between these indices, 0.99, means they move almost identically on a day-to-day basis. This correlation coefficient indicates that holding both provides essentially no additional diversification benefit; they are effectively substitutes, not complements.
| Metric | S&P 500 (VOO) | CRSP Total Market (VTI) |
|---|---|---|
| Correlation Coefficient | 0.99 (Extremely high positive correlation) | |
| R-squared | ~0.98 | |
| Volatility | 3.39% | 3.57% |
| 10-Year Standard Deviation | 14.7% | 15.2% |
| Maximum Drawdown (Since Inception) | -33.99% | -55.45%* |
| Sharpe Ratio | 0.45 | 0.44 |
| Beta vs. Market | 1.0 | 1.0 |
*VTI's larger maximum drawdown reflects its longer operating history (inception 2001 vs. 2010 for VOO), capturing the 2008 financial crisis. This difference does not indicate that small-caps are inherently twice as risky; rather, VOO simply did not exist during the worst market decline in modern history. Had VOO existed in 2008, its maximum drawdown would have been comparable.
The Volatility Trade-off
The CRSP Total Market Index exhibits marginally higher volatility (15.2% vs. 14.7% standard deviation) due to its small-cap exposure. Small-cap stocks are inherently more volatile than large-caps, which translates to slightly wider price swings. However, the difference is modest enough that most investors wouldn't notice it in practice. This minor increase in volatility is the "price" of broader diversification.
Dividend Analysis
Both indices historically yield between 1.2% and 1.6% with quarterly distributions, making dividend considerations largely irrelevant to the choice between them. The similarity exists because large-cap stocks, which dominate both indices, drive the yield calculation.
| Metric | S&P 500 (VOO) | CRSP Total Market (VTI) |
|---|---|---|
| Historical Dividend Yield Range | 1.2%–1.6% | 1.2%–1.6% |
| Dividend Frequency | Quarterly | Quarterly |
| Distribution Months | Mar, Jun, Sep, Dec | Mar, Jun, Sep, Dec |
Note: Dividend yields fluctuate with market conditions and price levels. Verify current yields on fund provider websites.
S&P 500 Dividend Characteristics
Companies are selected partly based on profitability and financial viability, resulting in more established dividend-paying companies. According to Hartford Funds research, dividends and their reinvestment have historically accounted for a substantial portion of total S&P 500 return over long periods.
CRSP Total Market Dividend Characteristics
Includes growth-oriented small caps that typically don't pay dividends, offset by small-cap value stocks that sometimes offer higher yields. The yield spread between indices is typically less than 0.1%.
Expense Ratios & Costs
The primary ETFs tracking these indices charge identical expense ratios, eliminating cost as a deciding factor. Vanguard's offerings, VOO for the S&P 500 and VTI for the total market, both charge 0.03%, meaning you pay approximately $30 per year for every $100,000 invested.
| Fund | Index Tracked | Expense Ratio | AUM |
|---|---|---|---|
| VOO (Vanguard S&P 500 ETF) | S&P 500 | 0.03% | $300B+ |
| VTI (Vanguard Total Stock Market ETF) | CRSP Total Market | 0.03% | $1.9T+ |
| IVV (iShares Core S&P 500 ETF) | S&P 500 | 0.03% | $500B+ |
| ITOT (iShares Core S&P Total U.S. Stock Mkt ETF) | S&P Total Market | 0.03% | $60B+ |
| SPY (SPDR S&P 500 ETF) | S&P 500 | 0.0945% | $500B+ |
Mutual Fund Equivalents
For investors who prefer mutual funds, Vanguard offers VFIAX (Vanguard 500 Index Admiral) tracking the S&P 500 at 0.04%, and VTSAX (Vanguard Total Stock Market Admiral) tracking the CRSP Total Market at 0.04%. The additional 0.01% cost versus ETFs is negligible for most investors and may be offset by automatic dividend reinvestment and fractional share purchases.
Pros and Cons
S&P 500 Advantages
- Lower Volatility: Slightly less volatile than total market due to large-cap focus
- Quality Screen: Committee selection includes financial viability requirement
- Liquidity: All components are highly liquid with tight spreads
- Recognition: Most widely followed benchmark globally
- Recent Outperformance: Slight edge in recent decades during large-cap dominance
- Simplicity: Easy to understand (500 largest companies)
S&P 500 Disadvantages
- Concentration Risk: Top 10 holdings represent ~38% of index
- Missing Small Caps: No exposure to small/micro-cap growth potential
- Committee Discretion: Selection not purely rules-based
- Selection Lag: Committee decisions can delay inclusion of fast-growing companies. For example, Super Micro Computer (SMCI) wasn't added to the S&P 500 until March 2024, after the stock had already risen over 700% from its 2022 lows driven by AI server demand. Total Market investors captured this growth automatically, while S&P 500 investors missed the bulk of the gains waiting for committee approval.
- Sector Imbalance: Tech at 34.6% creates significant concentration
- Limited Diversification: Only 500 companies vs. entire market
CRSP Total Market Advantages
- Comprehensive Coverage: ~100% of investable U.S. market
- True Diversification: ~4,000 companies across all market caps
- Small-Cap Exposure: Access to potential high-growth smaller companies
- Rules-Based: Transparent, objective methodology
- Academic Foundation: Developed by CRSP (University of Chicago affiliate)
- Lower Concentration: Slightly less concentrated in top holdings
- Direct Indexing Synergy: For high-net-worth investors, the Total Market approach is where Direct Indexing adds the most value. By owning individual stocks instead of an ETF, you can harvest losses on those 3,500+ small-cap stocks that the S&P 500 misses, generating tax alpha while maintaining broad market exposure.
CRSP Total Market Disadvantages
- Higher Volatility: Small-cap exposure increases overall volatility
- Marginal Small-Cap Impact: Despite 3,500+ extra stocks, only ~13% of index weight
- Illiquidity in Micro-Caps: Some holdings trade infrequently
- Similar Performance: Difference from S&P 500 often negligible
- Complexity: More holdings to track and understand
Which Index Is Right for You?
Choose S&P 500 If You:
- Prefer slightly lower volatility
- Want exposure only to established, large companies
- Value the quality screen of committee selection
- Prioritize liquidity and tight bid-ask spreads
- Seek the most recognized benchmark for comparison
- Are making short-to-medium term tactical allocations
Choose CRSP Total Market If You:
- Want the broadest possible U.S. equity exposure
- Believe in long-term small-cap premium potential
- Prefer transparent, rules-based index construction
- Have a very long investment horizon (20+ years)
- Want a "one-fund" U.S. equity solution
- Value academic/research-quality methodology
Either Choice Works If You:
- Are a long-term passive investor
- Accept that performance differences will likely be minimal
- Prioritize low costs (both available at 0.03%)
- Want broad U.S. market exposure
- Plan to buy and hold for decades
- Understand both are excellent choices
Key Takeaways
Performance converges over time. Over extended periods, returns are nearly identical, just 0.03% annual difference since 1957. This happens because large-cap stocks dominate both indices, and short-term variations in small-cap performance wash out over decades. Neither approach has demonstrated persistent superiority.
Correlation is extremely high. At 0.99, these indices move almost identically. Holding both provides essentially no diversification benefit. You should choose one or the other, not both. They are substitutes, not complements.
Large caps drive returns regardless of index. The S&P 500's 500 largest stocks represent approximately 87% of the CRSP Total Market Index by weight. This explains both the high correlation and the performance convergence. The additional 3,500 stocks in the total market index simply don't move the needle significantly.
Sector weights are similar. Due to market-cap weighting, sector allocations differ by only a few percentage points. Neither approach provides meaningfully different sector exposure.
Dividends match. Both historically yield between 1.2% and 1.6% with quarterly distributions. Income considerations don't favor either approach.
Costs are identical. The primary ETFs (VOO and VTI) both charge 0.03%, eliminating cost as a deciding factor. This decision should be based on philosophy and preference, not fees.
Volatility trade-off is modest. The total market index is slightly more volatile (15.2% vs. 14.7% standard deviation) due to small-cap exposure. For most investors, this difference is imperceptible in practice.
The practical difference is minimal. For most investors, either choice will produce similar outcomes over a multi-decade horizon. The more important decisions are: staying invested, keeping costs low, maintaining appropriate asset allocation, and avoiding behavioral mistakes. The S&P 500 vs. total market choice ranks far below these factors in terms of impact on long-term wealth.
"The choice between the S&P 500 and total market index is one of the least consequential decisions a long-term investor faces. Both provide excellent, low-cost exposure to U.S. equities. Pick the one that resonates with your investment philosophy, then focus your attention on the decisions that actually matter: savings rate, asset allocation, and staying the course."
Foxholm Financial Research
Disclaimer
This guide provides general educational information about index funds and is not personalized investment advice. Index characteristics, expense ratios, and performance data can change; verify current information on fund provider websites before investing. Past performance does not guarantee future results, and all investments carry risk, including the possible loss of principal. The funds mentioned are examples and not specific recommendations. Consider your own financial situation, risk tolerance, and investment objectives before making investment decisions. Consult with a qualified financial advisor who can evaluate your specific circumstances.