A beginner’s guide to Asia’s major stock indices

If you follow financial news, you have seen the headlines: the Nikkei 225 jumps, the Hang Seng slides, the Sensex hits a record. But what do these Asian stock indices actually measure, and why do investors around the world treat them as a daily health check on the region’s economies? This beginner’s guide explains the major Asia-Pacific benchmarks — what each one tracks, how it is built, and how to read its moves without being misled.

A stock index is simply a basket of selected shares designed to summarise a whole market in a single number. When the index rises, the companies inside it are worth more on average; when it falls, they are worth less. The details of which companies are included and how their weights are calculated change the story each index tells — which is exactly why it pays to know the difference.

What a stock index really measures

Every index follows a rulebook. That rulebook decides which companies qualify, how often the list is reviewed, and how much influence each stock has on the final figure. The two most common weighting methods are:

• Price-weighted — a company’s influence depends on its share price, not its size. A stock trading at a high nominal price can swing the index even if the business is smaller than a lower-priced rival.
• Market-capitalisation weighted — a company’s influence depends on its total market value (share price multiplied by shares outstanding). The biggest companies move the index most.

This distinction is not academic. It is the single most useful thing a beginner can learn about indices, because it explains why a benchmark can rise on a day when most of its members actually fell — a handful of heavyweight stocks simply pulled it along.

The heavyweights of North Asia

Japan: the Nikkei 225 and TOPIX

Japan’s Nikkei 225 is the most quoted benchmark in Asia and one of the oldest in the world. It tracks 225 large, established companies listed in Tokyo and is price-weighted, so expensive shares carry outsized influence. Alongside it sits the TOPIX, which covers a far broader sweep of the market and is weighted by company size, giving a more representative picture of the Japanese economy as a whole.

Greater China: Hang Seng, Shanghai Composite and CSI 300

In Hong Kong, the Hang Seng Index follows the territory’s largest listed companies, including many mainland Chinese firms that choose to list there. On the mainland, the Shanghai Composite reflects shares listed in Shanghai, while the CSI 300 blends the biggest companies from both Shanghai and Shenzhen into one market-cap-weighted benchmark that is widely used to gauge Chinese equities.

South Korea: the KOSPI

South Korea’s KOSPI is dominated by electronics, shipbuilding and carmaking giants. Because the index leans heavily on a small number of very large exporters, it is often read as a barometer of global demand for technology and manufactured goods — which also makes it sensitive to the semiconductor cycle. For more on that, see our explainer on why Taiwan and South Korea dominate the chip supply chain.

South and Southeast Asia

India has two headline benchmarks. The Sensex is a 30-company index of the largest firms on the Bombay Stock Exchange, while the broader Nifty 50 tracks 50 companies on the National Stock Exchange. Both are market-cap weighted and are watched closely as India’s economy grows in global importance.

Across Southeast Asia, each market keeps its own gauge: Singapore’s Straits Times Index (STI), Indonesia’s Jakarta Composite, Malaysia’s FTSE Bursa Malaysia KLCI, Thailand’s SET Index, the Philippines’ PSEi and Vietnam’s VN-Index. These markets are smaller than North Asia’s giants but are increasingly relevant as regional supply chains deepen — a theme explored in why the Asia-Pacific drives so much of global growth.

Oceania: the S&P/ASX 200

Australia’s main benchmark, the S&P/ASX 200, is heavily weighted toward banks and mining companies. That concentration makes it unusually sensitive to commodity prices and to demand from China, Australia’s largest trading partner. When iron ore or lithium prices move, the ASX 200 often feels it quickly.

Why the differences matter when you read the news

Because indices are built differently, they can tell different stories on the same day. A price-weighted index can be dragged up or down by one expensive stock; a market-cap-weighted index reflects the fortunes of its largest members; and a tech-heavy benchmark will react very differently from a bank-heavy one to the same interest-rate decision. Keep three questions in mind:

1. What does this index actually contain — one sector, or the whole market?
2. How is it weighted — by price or by company size?
3. Is today’s move broad-based, or driven by a few heavyweight names?

Answer those and you will read Asian market headlines far more clearly than someone who simply watches the number go up or down.

How to start following Asian indices

You cannot invest directly in an index — it is a measure, not a product. Instead, investors track them through index funds and exchange-traded funds (ETFs) that hold the same basket of shares, or simply use the index as a reference point for how a market is doing. For beginners, the practical steps are to pick one or two benchmarks relevant to the markets you care about, learn what they contain, and follow them consistently rather than flitting between dozens of numbers.

One quirk worth remembering is time zones. Asian markets open and close while much of the West is asleep, so a big overnight move in Tokyo or Hong Kong often sets the tone for European and American trading the next morning. Reliable figures are published by the exchanges themselves and by major financial-data providers, usually with a short delay for free sources.

Common mistakes to avoid

Beginners often read too much into a single day’s move, or compare indices that are not really comparable. A 1% change in a narrow, price-weighted index is not the same event as a 1% change in a broad, market-cap-weighted one. It is also easy to forget currency effects: for a foreign investor, returns depend not just on the index but on how the local currency moves — a point closely tied to central-bank policy, as explained in our look at the Bank of Japan and the yen.

• Don’t over-interpret one day’s move — look at the trend.
• Compare like with like: check weighting and sector mix first.
• Remember currency swings affect a foreign investor’s actual return.

Frequently asked questions

What is the most important stock index in Asia?

There is no single most important index, but Japan’s Nikkei 225 is the most widely quoted, while China’s CSI 300, Hong Kong’s Hang Seng, South Korea’s KOSPI and India’s Nifty 50 and Sensex are also closely watched. Which one matters most depends on the market you are interested in.

What is the difference between a price-weighted and a market-cap-weighted index?

In a price-weighted index such as the Nikkei 225, stocks with higher share prices have more influence regardless of company size. In a market-cap-weighted index such as the CSI 300 or Nifty 50, the largest companies by total market value have the most influence.

Why does the ASX 200 move with commodity prices?

Australia’s S&P/ASX 200 is heavily weighted toward mining companies and banks, so swings in commodity prices and in demand from China tend to show up quickly in the index.

Can an index rise even if most of its stocks fall?

Yes. If a few heavily weighted companies rise sharply, they can pull the whole index up even while the majority of its members decline — which is why it helps to know how an index is weighted.

The bottom line

Asia’s stock indices are shorthand for the health of the region’s economies, but each one is built on its own rules. Learn what a benchmark contains and how it is weighted, and its daily moves start to make sense. That simple habit is the foundation of reading Asian markets with confidence.