The U.S. Stock Market at a Glance
You often hear on the news that 'the S&P 500 rose' or 'the Nasdaq fell.' Yet surprisingly few people really know what these indexes contain and what the U.S. stock market actually looks like.
The world's largest stock market
The U.S. is the country with the world's largest stock market. As we saw earlier, at the end of 2024 about half of the world's stock market capitalization was concentrated in the U.S.
U.S. stocks are traded largely on two exchanges. One is the New York Stock Exchange (NYSE), the other is the Nasdaq. Each has a market capitalization of around $30 trillion, making them the world's No. 1 and No. 2 exchanges.
Even for the same U.S. stock, its character differs slightly depending on which exchange it's listed on and which 'index' it's included in.
What's different about the NYSE and Nasdaq
The NYSE (New York Stock Exchange) is a traditional exchange with over 200 years of history. Many older, large industrial, financial, and consumer-goods companies are listed there.
The Nasdaq is an electronic-trading-centered market launched in 1971, with an especially large number of tech stocks. Think of names like Apple, Microsoft, Nvidia, and Amazon.
Both are markets that represent the U.S., so rather than 'which is better,' it's enough to understand that the character of listed companies and the trading method differ (the NYSE is a designated-market-maker auction, the Nasdaq is a dealer method).
A Nasdaq listing doesn't automatically mean a tech stock, nor is every NYSE-listed company an old-line firm. It's only a rough tendency.
The four flagship indexes: S&P 500, Dow, Nasdaq Composite, Russell 2000
There are four flagship indexes that summarize the U.S. market.
- S&P 500 — holds 500 large U.S. companies (actually 503 stocks, due to multiple share classes). It covers about 80% of U.S. stock market cap, so it's used most often to view 'the whole U.S. market.' Market-cap weighted (larger companies get a larger weight).
- Dow Jones Industrial Average (DJIA) — holds just 30 blue-chip companies. Moreover, because it is 'price weighted,' stocks with high share prices have a large influence. It has a long history and appears often in the news, but its representativeness is narrower than the S&P 500's.
- Nasdaq Composite — holds more than 2,500 stocks listed on the Nasdaq. It has a high weighting in tech stocks.
- Russell 2000 — holds about 2,000 small-cap stocks. It's a window into the health of U.S. small and mid-sized companies.
Even for the same 'U.S. stocks,' the rises and falls can look different depending on which index you view.
Preguntas frecuentes
Q. Why is the Dow Jones so famous when it holds only 30 companies?
It's because it's the longest-running index, calculated since 1896. Being old, it appears often in the news, but with only 30 stocks and a price-weighted method, its power to represent the whole market is weaker than the S&P 500's. To view the U.S. market overall, the S&P 500 is more widely used.
Q. If I invest in U.S. stocks from Korea, am I also affected by the exchange rate?
Yes. Because U.S. stocks are traded in dollars, even if the share price stays the same, if the KRW/USD exchange rate rises or falls, your return converted into won changes. Don't forget that overseas investing requires looking at 'price movement + exchange-rate movement' together.
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