What Is a Stock Market Index? A Beginner's Guide for Saudi Investors

The Problem That Indices Solve

It can be hard to visually see how stock activity performs in the stock market; however, since there are so many companies (more than 5,000) involved in the stock market, it is impossible to track them all at once on a daily basis without a summary measure of their stock prices. This means one would never be able to determine whether the stock market was up or down for any given day. The stock market index addresses this by calculating a single numerical value that lists the collective stock performance of a specific amount of stocks, thereby allowing anyone to know instantly if the market is trending up or down and how strong that trend may be.

Indices also serve as benchmarks. If your Saudi investment portfolio returned 12% last year, that number means little without context. Against an S&P 500 that returned 16%, your 12% underperformed. Against a TASI that fell 11%, your 12% was outstanding. Indices provide the reference points that make objective performance evaluation possible.

How Is a Stock Market Index Constructed?

Market Capitalisation Weighting — The Most Common Method

The vast majority of modern indices including the S&P 500, Nasdaq Composite, TASI, and MSCI World are market-capitalisation weighted. Each company's representation in the index is proportional to its market cap (share price multiplied by shares outstanding). Larger companies have more influence on daily index movements than smaller ones.

Apple accounts for approximately 7% of the S&P 500 Index, therefore, a 10% increase (or decrease) in its stock price would have 7 times the effect on the entire index than would a 10% change in a company which represents 1% of the S&P 500 Index. Investors of market-value weighted index funds are essentially placing much larger amounts of money in the largest companies, which has tended to be a profitable strategy when the largest technology companies have had strong performance.

Price Weighting — An Older Methodology

With its measure of price-weighted indices and the weighting by price method, the DOW gives disproportionate influence to stocks with large prices over those of a small firm, regardless of their overall size or profitability. Thus, at $ 500 per share, Goldman Sachs has more of an influence on the DOW than does Apple at $220 per share, even though Apple, with its greater market capitalization, is by far the more substantial company. Consequently, many professional investors believe that the S&P 500 is much more relevant than the DOW.

The Most Important Stock Market Indices for Saudi Investors

The S&P 500 — The Global Standard

Standard & Poor’s 500 Index (S&P 500) measures 500 of the largest public US corporations based on their total market cap. The index was created in 1957 and is one of the most commonly referenced indices for stock performance in the world and globally for institutional portfolio measurement. As the economy of the U.S. has changed over time, so too has the S&P 500, with an ever-increasing concentration on technology stocks like Apple, NVIDIA, Microsoft, Alphabet, Meta, and Amazon; followed by healthcare; financials; and consumer discretionary.

The S&P index has delivered an average total return on investment of 10.5% including reinvested dividends from 1957 through 2021, and it has always produced a positive total return no matter how long you invest. In addition, since 2021, the S&P has produced a return on investment above 0.0% every single year to date. If you would like to invest in the S&P as a result of your investment decisions in the current year, 2026 requires companies to have at least an $18 billion market capitalization, positive earnings in the last quarter and combined over the last four quarters, and at least 50% of shares are available for public trading.

The TASI — Tadawul All Share Index

Saudi Arabia's main stock market benchmark is the TASI, which is used for tracking every company's stock listed on the Saudi Exchange (Tadawul). As of March 2026, the TASI has an approximate market cap of SAR 8.8 trillion and is the largest equity market in the Middle East and North African area. This index is primarily made up of the financial services, energy, and petrochemical sectors, as evidenced by a greater than normal percentage of total TASI market cap being attributed to stock movement of Saudi Aramco. Thus, based on the stock's price movement, it will have a greater than average impact on changes to the TASI index.

Therefore as of March 2026, the index is currently trading at around 10,830 pts – a drop of around 11.94% from this time last year; this reflects both global geo-political events stemming from US/Israel air-strikes against Iran that occurred during February 2026. The trailing P/E ratio for the TASI - which is approximately 14.89x - is similar to the TASI's 10 year average P/E ratio of 15.17x indicating a fair market value rather than a high/low exit point on your investment.

The Nasdaq Composite

With an emphasis on technology, biotech, and high-growth industries, Nasdaq Stock Market tracks more than 3,000 publicly traded companies. Of these companies, the Nasdaq 100 represents one hundred of the largest publicly traded companies on Nasdaq (excluding banks) and is a benchmark for the technology industry. Due to the number of technology companies included in the Index, Nasdaq 100 has experienced higher volatility than S&P 500; this volatility has resulted in higher returns during bull markets but also larger losses during bear markets.

The Dow Jones Industrial Average

The most recognized index in America, the DJIA, launched in 1896, shows the performance of 30 companies with publicly traded common stock and is often viewed as the primary gauge for America’s stock market performance. Consequently, many analysts and portfolio managers use the S&P 500 Index to evaluate overall market conditions since it has a larger focus on a more complete picture of the broader market and is equal in regard to market capitalization.

MSCI Emerging Markets — Saudi Arabia's Global Connection

Saudi Arabia was added to the MSCI Emerging Markets Index in June 2019, a landmark event that brought significant foreign institutional capital into Tadawul-listed companies. Inclusion in a major global index creates a baseline of demand from international index fund managers who must hold representative Saudi equity positions. This event fundamentally changed the profile and liquidity of the Saudi market.

How to Read Index Performance Data

An article headline stating that "the S&P 500 decreased 1.2% today" denotes that the weighted average price of all companies in the S&P 500 fell by 1.2% compared to yesterday's close, while the specific index number (e.g., 6900) does not have the same meaning as the change from its previous designating date. Instead, what matters is whether it went up or down; and how much it went up or down relative to how it started off before that was changed.

YTD percentage change is reported frequently as a way to look at how much a security has changed in price so far this year versus how much it closed on 12/31/2022. The 52-week range indicates the high and low prices for the previous 52 weeks, which can help determine where the current price falls compared to historical prices.

Why Index Literacy Makes You a Better Investor

When you understand that the S&P 500 has recovered from every correction exceeding 10% in its history, a 10% portfolio drawdown becomes data rather than a panic trigger. When you understand that the TASI's correlation with oil prices means Aramco drives Saudi market direction, you can contextualise TASI movements more accurately.

Understanding indices also allows you to evaluate whether your portfolio is earning its risk, whether the returns you generate justify the concentration and active selection risk you take relative to simply owning a low-cost index fund and capturing market returns at minimal cost.

Related: What Is Market Capitalisation? Large-Cap, Mid-Cap, Small-Cap Explained

Frequently Asked Questions

Can I invest directly in the S&P 500 from Saudi Arabia?

You cannot buy the index itself, but you can invest in ETFs that track it. SPUS (Shariah-compliant) and VOO (standard) are both available on Raseed. Fractional investing means you can start with as little as $1.

What is the difference between an index and an ETF?

An index is a calculation, a number representing market performance. An ETF is an actual investable fund that holds the stocks of that index. The S&P 500 is the index; VOO, SPY, and SPUS are ETFs that track it. You invest in the ETF, not the index directly.

Disclaimer: This article is for educational and informational purposes only and does not constitute financial advice. All investing involves risk. Past performance does not guarantee future results. Securities brokerage services are provided by Fullerverse (SC) Limited, licensed and regulated by the Financial Services Authority Seychelles (Licence No. SD152), a wholly-owned subsidiary of Raseed Invest Inc. Capital is at risk.