Trading the S&P 500: What you should know
Trading indices gives you exposure to the broader markets. It is a great way to diversify your portfolio without having to spend on individual stocks.
To help you start your index trading journey, here’s the first of our series of educational guides.
Since the S&P 500 is the world’s most watched index, what better place to start?. Keep an eye on this space for our guides on other major global indices.
Understanding the S&P 500
Did you know that the Standard & Poor’s 500 (S&P 500 or US500 with Alpari) index hit 57 new all-time highs in 2024 alone?
The index recorded 25% gains through the year. The S&P 500, as we know it today, took shape in 1957, listing 500 stocks. The index was actually formed 34 years before this, with less than 100 companies.
The US benchmark index gets its name from Standard Statistical Bureau and Poor’s Publishing, the two companies that launched it as a joint project. On March 6, 2025, the broad-based index consisted of 504 common stocks of the top large-cap companies listed on the American stock exchanges.
It is widely considered the most significant gauge of the performance of US equities and the global markets. This is why it is among the most popularly traded indices and a key tool for trading decisions.
What is the S&P 500?
The S&P 500 is a float-weighted index based on market capitalisation. This means that the impact (or share) of a stock on the index is relative to the total number of shares available for trading and the stock’s market capitalisation. For a market cap-weighted index, such as the S&P 500, a more valuable company has a stronger impact on the overall performance.
The S&P 500 is rebalanced every quarter to ensure that it remains a reliable measure of the market’s overall performance.
For instance, Nvidia, the best-performing (+171.20%) US company of 2024 and the one with the second-highest market cap, played a critical role in the S&P 500’s performance that year. Nvidia surged 140% in the first three quarters of 2024, accounting for one-fourth of the S&P 500’s 17% gains during that period. On the same lines, Nvidia’s disappointing earnings in the first week of January 2025 weighed heavily on the index, contributing significantly to its 1.59% decline.
The S&P 500 is part of a family of indices – the S&P Global 1200. The family includes S&P MidCap 400 and S&P SmallCap 600, which represent the top 400 mid-cap and 600 small-cap companies. Given their depth and breadth, the S&P Global family is the go-to index for institutional investor to gauge market performance.
The S&P 500 uses only free-floating shares, i.e., ones available for public trading. The weight of member companies is adjusted after M&As, stock-splits, or when a company issues new shares. The index is rebalanced periodically to maintain relevance to changing market conditions and company performances. This rebalancing may involve only adjusting the weights or even adding/removing stocks from the index.
What qualifies a company for the index?
The S&P 500 has certain eligibility criteria for including a common stock in the index. These include:
- Minimum market cap: $8.2 billion
- Company type: Corporation based in the US with common stock
- Minimum shares: At least 250,000 for the six months preceding the date of evaluation (or rebalancing)
- Listing: Listed on one of the top US exchanges, such as the NASDAQ and NYSE
- Earnings: A positive report in the most recent quarter and on a trailing 12-month period
The average life span of a company in the S&P 500, when the index was created, was about 61 years, which shrank to 18 years by December 2023. With sustainability becoming the new trend, large companies that fail to disrupt may have to exit the index. This is expected to further reduce the life span of companies on the index during 2026 to 2030, after which it may rise further.
Sector: The MSCI’s Global Industry Classification Standard (GICS) is referenced to ensure sector balance in the index.
Limitations of S&P 500 index
The most prominent limitation of any market-cap-weighted index arises when a member stock is overvalued. This means the stock rises significantly higher than its fundamentals warrant. A heavy-weighted stock, when overvalued, disproportionately inflates the composite index, distorting its relevance for the market.
Why trade the S&P 500 index
There are several benefits of trading the global benchmark index:
Inherent diversification
The benefit of index trading is diversification. The S&P 500 includes all sectors by weight associated with their growth potential. Traders can get broad exposure to the largest publicly traded companies in the US.
This also makes the index theoretically less risky (theoretically being the keyword) than individual stocks. The presence of a wide range of companies makes your portfolio less vulnerable to a downturn in a specific sector or poor performance of one company’s stock. In other words, your portfolio is less exposed to non-systematic risk. Yet, for situations such as the bursting of the dot-com bubble, the pessimism spills across industries, weighing on the index’s performance.
Quick news absorption
The S&P 500 immediately reflects the market sentiment after important market reports, news breaks and earnings reports. This makes it a critical benchmark to follow for short- and medium-term traders.
High volatility and liquidity
Since the S&P 500 is traded globally, it reflects global market sentiment. This means the liquidity, or the possibility of getting orders filled faster, is high.
The CBOE volatility index (VIX) quantifies the volatility of the S&P 500 The VIX, therefore, is an important gauge of rising trading opportunities and risk-on sentiment among investors in general and in the S&P 500 index. VIX is also popularly called the fear gauge or fear index.
The day before the November 2024 US presidential election, the CBOE VIX stood at 22.45, more than 4 points above the average of the previous 35 years. This highlighted the heightened volatility and S&P 500 did not disappoint. The index surged 5.7% in the election month, making it the best month of 2024. Note that volatility does not indicate the direction of movement.
Understanding the VIX
Value
Interpretation
Significance
0-15
Low
Investor confidence in their positions
15-25
Moderate
Typical market environment
25-30
Rising
Market turbulence
>30
High
Extreme market swings
Low entry barrier
The S&P 500 can be traded directly or via contracts for difference (CFDs), which lower the upfront capital requirement. CFDs on indices (and other assets) are derivative instruments and can be used to explore opportunities during bear and bull runs. This ability makes CFDs popular among traders, since with CFDs, you are trading the index based on the speculated change in the direction of movement in either direction.
Plus, CFDs can be traded on margin with a leverage of up to 1:1,000. This means for every dollar you invest, the broker fills in $999, so that you get a purchasing power of $1,000. Exercising caution with that kind of power is critical as this amplifies potential profits and losses. This necessitates the use of robust risk management techniques on your index trading strategy.
Understanding the S&P 500’s movements
Comprehensive analysis is crucial for trading the S&P 500 index. Technical analysis is crucial to make informed decisions to exit or enter index trading positions. However, fundamental analysis considers all factors that impact the index’s movements.
Fundamental analysis includes:
Economic data
Economic data reflects on the health of the US economy. Therefore, they impact investor sentiment, ultimately moving the S&P 500 and other indices. Key economic indicators to look out for:
- GDP Growth: Strong GDP growth indicates a healthy economy, which propels positive market sentiment. This supports the stock market and the S&P 500.
- Interest Rates: Monetary easing encourages borrowing and business spending, which in turn stimulates the economy. On the other hand, high interest rates slow down business spending, especially associated with R&D and innovation. The resultant negative investor sentiment then weighs on the index.
- Inflation: Inflation is more a gauge of balance in the economy. While moderate inflation signals growth, high inflation indicates a decline in purchasing power. Exceptionally high inflation gives rise to bear sentiment.
- Job Reports: The rate of unemployment and jobs created are two important metrics that affect the S&P 500. Increasing employment indicates a potential surge in business activity, which fuels optimism among investors.
Corporate earnings
Company profits, operating margin, etc. determine the company’s performance and long-term viability. Its outlook indicates the leadership’s confidence in business growth. Earnings reports that surpass positive market speculations lead to a surge in individual stocks as well as wider sector sentiment. This drives the S&P 500 higher.
On the contrary, disappointing performance by a leading company, such as Amazon, may indicate a slump in the e-commerce sector, weighing on sectoral and index performance. Note that the impact on the S&P 500 is weighted.
Add an economic calendar to your trading tool kit to stay updated on upcoming earnings and economic data.
Geopolitical events
Political instability, trade wars and wider conflicts create uncertainty in the markets. This triggers equity sell-offs and pushes investors toward safe havens, such as gold or the US dollar. For instance, since President Trump’s announcement regarding tariffs in the second week of February 2025, the S&P 500 lost nearly 4% by March 6, 2025.
Technical analysis
Technical analysis includes:
Chart patterns
Candlestick patterns, such as head-and-shoulders and morning and evening star, help traders identify trend reversal and continuation.
Trend analysis
Trendlines and technical indicators, such as Bollinger Bands, can help determine the strength of a trend to make informed trading decisions.
Technical indicators
Technical indicators, such as MACD, ADX, ATR, etc., help traders gauge trading volume and momentum to make informed index trading decisions.
Best time to trade the S&P 500 index
Direct S&P 500 trading is available from 9:30 am to 4:00 pm EST (2:30 pm to 9:00 pm UTC) on all trading days. Traders popularly prefer the overlap of the UK and US trading hours, when more traders are active, boosting market liquidity. However, since index trading via CFDs is available 24 hours a day, you have the flexibility to trade at your preferred time.
Trading the S&P 500 Index
Alpari understands that traders need the peace of mind to focus on their trading. This is why they offer the assurance of a licensed and regulated trading environment in several jurisdictions across the world.
We also offer a demo account so you can refine your index trading strategy and learn to adapt to market conditions.
Register with Alpari for reliable free index trading education.
