What is Russell 2000 Index? (Plain English Definition)
Definition: The Russell 2000 is a stock market index that tracks the performance of 2,000 small-cap U.S. companies, serving as the primary benchmark for small-cap investing.
Russell 2000 Index Explained Simply
The Russell 2000 Index measures the performance of approximately 2,000 small-cap companies in the United States. These are the 2,000 smallest companies in the broader Russell 3000 Index, which represents roughly 98% of the total U.S. stock market. The Russell 2000 is the most widely followed benchmark for small-cap stock performance.
Small-cap companies in the Russell 2000 typically have market capitalizations between $300 million and $2 billion. These are generally younger, faster-growing companies compared to the large-caps in the S&P 500. The index spans all sectors but tends to have higher weightings in financials (many small regional banks), healthcare (biotechnology companies), and industrials.
Popular ETFs tracking the Russell 2000 include the iShares Russell 2000 ETF (IWM) and the Vanguard Russell 2000 ETF (VTWO). Small-cap stocks have historically offered slightly higher returns than large-caps over very long periods, but with significantly more volatility. The small-cap premium is one of the most debated topics in academic finance.
Russell 2000 Index Example
The iShares Russell 2000 ETF (IWM) holds approximately 2,000 small-cap stocks with a median market cap around $1 billion. From 2000 to 2020, the Russell 2000 returned about 7.5% annually compared to about 6.1% for the S&P 500 -- a small-cap premium of 1.4% per year. However, IWM's volatility was about 20% higher, and it experienced sharper declines during recessions. The extra return came at the cost of a significantly bumpier ride.
Why Russell 2000 Index Matters for ETF Investors
The Russell 2000 is important for ETF investors who want to diversify beyond large-cap stocks. Small-cap companies represent a different part of the economy -- more domestic-focused, more growth-oriented, and more sensitive to the U.S. economic cycle. For ETF investors, a small allocation to a Russell 2000 or total small-cap ETF can enhance portfolio diversification. Small-caps do not always move in lockstep with large-caps, providing some diversification benefit. However, because total market ETFs like VTI already include small-caps in their market-cap proportion, adding a dedicated small-cap ETF means deliberately overweighting this segment -- a decision that should be intentional and aligned with your risk tolerance.
Russell 2000 Index vs Small-Cap
| Russell 2000 Index | Small-Cap |
|---|---|
| The Russell 2000 is a stock market index that tracks the performance of 2,000 small-cap U.S. companies, serving as the primary benchmark for small-cap investing. | See full definition of Small-Cap |
While russell 2000 index and small-cap are related concepts, they serve different purposes in the world of ETF investing. Understanding both terms helps you make more informed decisions about which funds to include in your portfolio and how to evaluate their performance.
Related Terms
Deepen your understanding of ETF investing by exploring these related concepts:
Small-Cap
Small-cap refers to companies with a market capitalization typically between $300 million and $2 billion, representing smaller, often faster-growing companies.
Large-Cap
Large-cap refers to companies with a market capitalization typically above $10 billion, representing the biggest and most established publicly traded companies.
Mid-Cap
Mid-cap refers to companies with a market capitalization typically between $2 billion and $10 billion, positioned between large and small companies in size.
S&P 500 Index
The S&P 500 is a stock market index tracking 500 of the largest U.S. companies, widely considered the best single measure of U.S. stock market performance.
Index
An index is a standardized collection of securities that represents a specific segment of the financial market, used as a benchmark to measure performance.
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