What Is the S&P 1500? Complete Investor Guide

The S&P Composite 1500 — its official name — is a stock market index managed by S&P Dow Jones Indices. It was launched in 1995 to provide a single benchmark covering the vast majority of the investable U.S. equity market.

• Composition:S&P 500 (large-cap) + S&P MidCap 400 + S&P SmallCap 600 = 1,500 companies
• Coverage: Approximately 90% of total U.S. equity market capitalization
• Quality screen: Every constituent must demonstrate positive earnings, adequate trading liquidity, appropriate sector representation, and sufficient public float
• Managed by:S&P Dow Jones Indices, with quarterly reviews and changes as needed

The quality screen is what sets the S&P 1500 apart from broader indices. You cannot simply be a U.S.-listed company to qualify — you must be a profitable, liquid, U.S.-listed company. This filter removes thousands of speculative, money-losing, or thinly-traded stocks that would add noise to any screening process.

The S&P 1500 is not constructed from scratch — it is the union of three well-known indices, each covering a distinct market-cap segment:

Companies can move between the three sub-indices during reconstitution. A small-cap company that grows into midcap territory may be promoted from the S&P 600 to the S&P 400 — and eventually to the S&P 500 if it reaches large-cap scale. Conversely, a declining large-cap may be relegated from the 500 to the 400. Throughout these transitions, the company remains in the S&P 1500.

All three sub-indices apply the same quality criteria: positive trailing four-quarter earnings, minimum trading volume, minimum public float, and organizational viability. This makes the S&P 1500 a fundamentally higher-quality universe than indices that rely on market capitalization alone.

There are several reasons why investors — and stock screeners — benefit from using the S&P 1500 rather than the S&P 500 alone:

• Broader diversification.The S&P 500 is dominated by a handful of mega-cap technology companies. The S&P 1500 dilutes this concentration by including 1,000 additional midcap and small-cap firms across every sector.
• More alpha opportunities.The highest-scoring stocks in a multi-model screener are disproportionately found in midcap and small-cap territory, where analyst coverage is thinner and pricing inefficiencies are more common. Restricting yourself to the S&P 500 means ignoring two-thirds of the quality-screened universe.
• Better economic representation.The S&P 500 over-represents global technology giants and mega-cap healthcare firms. The S&P 1500 includes the regional banks, specialty manufacturers, and niche service companies that more accurately reflect the breadth of the American economy.
• Institutional benchmark.Many institutional investors and plan sponsors use the S&P 1500 as their primary U.S. equity benchmark precisely because it captures the full spectrum of quality-screened companies across all market cap segments.

The S&P 1500 is not the only broad U.S. market index. Here is how it compares to the alternatives:

The Russell 3000includes approximately 3,000 stocks based purely on market capitalization. This means it contains many unprofitable companies, including pre-revenue biotechs, SPACs, and recently-IPO'd companies with no track record. For passive investing, this breadth may be fine. For fundamental screening, it introduces noise.

The Wilshire 5000 (which today contains closer to 3,500 stocks despite its name) goes even broader, including some OTC-traded securities with minimal liquidity. The CRSP Total Market Index, used by Vanguard's popular VTI fund, is similarly comprehensive but unfiltered.

The S&P 1500's advantage for stock screening is its quality gate. By requiring positive earnings and adequate liquidity, it pre-filters the universe to companies that are actually analyzable using fundamental models like Graham Fair Value, Piotroski F-Score, and Greenblatt Magic Formula. Running these models on money-losing micro-caps would produce meaningless scores.

AlphaStocks scores 1,595 stocks daily: the full S&P 1500 plus select ADRs (American Depositary Receipts) of major international companies. Every stock receives the same rigorous five-model evaluation:

• Consistent methodology. The same composite scoring formula applies to every stock, whether it is in the S&P 500 or the S&P SmallCap 600. The same four axes, same weights, same daily recalculation.
• Sector calibration. While the formula is consistent, the model inputs are calibrated for each sector. A bank is scored using bank-appropriate metrics (net interest margin, provision coverage), not the same ratios applied to a software company. Seven sector profiles ensure fair cross-sector comparison.
• Cross-cap comparison.Because the methodology is identical across market caps, you can meaningfully compare a large-cap stock's score to a midcap or small-cap stock's score. A composite score of 8.0 means the same thing regardless of company size.
• Walk-forward validated.The composite formula was designed on 2021-2023 data, then locked and tested out-of-sample on 2024-2026 data. The top 30 highest-scoring S&P 500 stocks delivered +8.4% annual alpha during the out-of-sample period. See the backtest results for full details and disclaimers.

Use the stock screener to filter across the entire S&P 1500 universe, or browse pre-built rankings like Top Composite Scores to see which stocks are scoring highest across all market cap segments right now.