Major global indices explained: S&P 500, Nasdaq 100, Dow Jones and Nikkei 225

When financial news reports that "the market was up today," they are usually referring to an index. Indices are the benchmarks that define how markets perform. Understanding what they are, how they are constructed and what they measure is foundational knowledge for anyone trading equities, index products or tokenized versions of market benchmarks.

Key takeaways:

• A stock market index tracks the performance of a selected group of stocks, providing a single number that represents the overall direction of a market or sector.

• Different weighting methodologies (market-cap-weighted, price-weighted or equal-weighted) fundamentally affect how individual stocks influence the index level.

• The major global indices (S&P 500, Nasdaq 100, Dow Jones, FTSE 100, Nikkei 225 and others) each represent distinct economic exposures, regional strengths and sector biases.

What is a stock market index?

A stock market index is a statistical measure that tracks the combined performance of a selected group of stocks. Constituent stock prices determine the index value, weighted according to a specific methodology. When constituent stocks rise in aggregate, the index rises. When they fall, the index falls.

Indices serve several critical purposes in global finance:

• Benchmarking: Fund managers compare their returns to an index to show whether they are generating performance above the static market return. An actively managed fund that consistently trails its benchmark index raises a serious question about whether the management fee is justified.

• Market sentiment: Index levels give investors a quick read on whether the market is broadly optimistic or pessimistic about economic conditions.

• Tradable products: Futures contracts, options, ETFs and tokenized index products let investors gain exposure to index performance without buying every underlying stock individually.

Index construction methodologies

How an index weights its constituents determines which stocks have the most influence on its overall movement.

• Market-cap weighting: The most common methodology. Each stock's weight is proportional to its total market capitalization (share price multiplied by outstanding shares). Larger companies carry significantly more influence. The S&P 500 and Nasdaq 100 both use this approach.

• Price weighting: Each stock's weight is proportional to its share price, regardless of the company's actual size. In a price-weighted index like the Dow Jones, a company with a $300 share price has ten times the influence of a company with a $30 share price, even if the $30 company is a much larger business by overall market value.

• Equal weighting: Each constituent carries the same weight regardless of size or price. Equal-weighted indices give more exposure to smaller companies and tend to behave differently from their cap-weighted equivalents during major market shifts.

For a closer look at how these weighting methods impact performance, read the full guide on cap-weighted vs. price-weighted vs. equal-weighted indices.

The major indices at a glance

The major global indices

S&P 500 (United States)

The S&P 500 tracks 500 large-cap US companies across all sectors. It is market-cap weighted and rebalanced quarterly. Investors and fund managers worldwide treat it as the primary benchmark for US equity performance and the closest single proxy for the overall health of the US economy. When most people refer to "the stock market," they typically mean the S&P 500.

Nasdaq 100 (United States)

The Nasdaq 100 tracks the 100 largest non-financial companies listed on the Nasdaq exchange. It is heavily weighted toward mega-cap technology and growth companies including Apple, Microsoft, NVIDIA, Amazon and Meta. The Nasdaq 100 is typically more volatile than the S&P 500 and tends to significantly outperform during risk-on economic environments when capital flows toward high-growth sectors.

Dow Jones Industrial Average (United States)

The oldest and most widely recognized US index, the Dow Jones tracks 30 blue-chip US companies. Its price-weighted methodology and small constituent count make it a less precise measure of the broad US economy than the S&P 500. Despite this limitation, it remains an important psychological benchmark widely followed by retail investors and financial media.

FTSE 100 (United Kingdom)

The FTSE 100 tracks the 100 largest companies listed on the London Stock Exchange by market capitalization. It carries a heavy concentration of legacy financials, energy conglomerates and mining companies, making it highly sensitive to global commodity cycles and less reflective of the modern technology economy than US indices.

Nikkei 225 (Japan)

The Nikkei 225 tracks 225 large-cap companies listed on the Tokyo Stock Exchange. Like the Dow Jones, it is price-weighted. The Nikkei is the primary benchmark for the Japanese equity market and tends to move inversely to the strength of the yen: a weaker currency boosts the reported earnings of its export-heavy constituents, lifting the index.

DAX (Germany)

The DAX tracks the 40 largest companies listed on the Frankfurt Stock Exchange. Unlike most major indices, the DAX is a total return index, meaning it automatically factors reinvested dividends into its calculation. The DAX is heavily weighted toward industrials, chemicals and automotive manufacturing, making it a barometer for European and global manufacturing health.

Hang Seng (Hong Kong)

The Hang Seng tracks the largest companies listed on the Hong Kong Stock Exchange. It includes major Chinese technology and real estate companies and serves as the default international benchmark for exposure to Chinese and Hong Kong corporate equities. The index is particularly sensitive to policy developments from Beijing and shifts in global risk appetite toward emerging markets.

The evolution of index trading

Indices are mathematical constructs and cannot be bought or sold directly. Over the decades, financial innovation has created a series of instruments to give investors index exposure:

1. Index futures: Standardized contracts to buy or sell the cash value of an index at a future date and price. Primarily used by institutional traders for hedging and directional exposure.

2. Index ETFs: Exchange-traded funds that hold constituent stocks in proportion to the index weighting, opening index investing to retail portfolios at low cost.

3. Index options: Derivative contracts giving traders the right (but not the obligation) to buy or sell the value of an index at a specific price. Commonly used for portfolio hedging or leveraged directional trades.

4. Tokenized index products: The latest evolution in market access. These on-chain instruments track traditional index performance via blockchain infrastructure, offering 24/7 exposure and fractional settlement.

The bottom line

Global indices are the scorecards of financial markets. Each tells a different story: the S&P 500 reflects broad US corporate health, the Nasdaq 100 reflects technology sector momentum, the Nikkei reflects Japanese export competitiveness and the FTSE 100 reflects global commodity and financial cycles.

Understanding what each index measures, how it is weighted and what macroeconomic forces drive it gives you the context needed to navigate global markets confidently. Index CFDs on platforms like Bybit TradFi now make it possible to access these benchmarks 24/7 from a single crypto account, with fractional settlement and no need for a traditional brokerage.

Ready to explore index trading? Visit Bybit TradFi to get started today.

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