What Is a Stock Index?
A stock index measures the value of a specific section of the stock market. The FTSE 100 tracks the 100 largest companies on the London Stock Exchange. The S&P 500 tracks 500 large US companies. The DAX 40 covers the top German companies. Each index is calculated using either price-weighting or market-cap-weighting of its component stocks.
When you trade an index CFD, you're speculating on the direction of the entire index — not individual stocks within it.
Why Trade Indices?
Index trading offers built-in diversification. Instead of betting on a single company, you're trading the aggregate performance of dozens or hundreds of stocks. This reduces the impact of any single company's bad news on your position.
Indices also tend to have tighter spreads and deeper liquidity than individual share CFDs. They respond strongly to macroeconomic events, central bank decisions, and broad market sentiment — making them popular with both technical and fundamental traders.
The Major Global Indices
The most traded indices worldwide include:
- S&P 500 (US) — 500 large-cap US companies, market-cap weighted
- FTSE 100 (UK) — 100 largest companies on the LSE
- DAX 40 (Germany) — top German blue-chip stocks
- Nikkei 225 (Japan) — 225 leading Japanese companies
- NASDAQ 100 (US) — 100 largest non-financial companies on NASDAQ, heavily tech-weighted
What Moves Index Prices
Indices react to corporate earnings seasons, central bank policy changes, employment data, GDP releases, and geopolitical developments. Tech-heavy indices like the NASDAQ are particularly sensitive to interest rate expectations, while commodity-heavy indices respond more to raw material prices.
Index CFDs also trade outside regular stock market hours on most platforms, allowing you to react to overnight developments before the underlying exchange opens.
Key Takeaways
- Index CFDs let you trade entire markets through a single position
- Built-in diversification reduces single-company risk
- Major indices include the S&P 500, FTSE 100, DAX 40, and Nikkei 225
- Driven by macro data, central banks, earnings seasons, and sentiment
- Often available to trade outside regular stock exchange hours
