How the Stock Market Works: A Clear Guide for New Zealanders

The stock market is where people buy and sell shares, small slices of ownership in companies. Here is how the stock market works in New Zealand, in one line: companies list on the NZX, investors trade through a broker or platform, and every price is simply the last point where a buyer and a seller agreed. Indices, news and dividends all build on that.

What is a share, and why do companies sell them?

A company that wants to grow needs money. It can borrow, or it can sell part of itself to investors. Shares are those parts. Own 1,000 shares in a company that has issued 10 million, and you own 0.01% of it: a small claim on its profits, its assets and its votes.

The company receives money only when it issues shares: at its listing (an initial public offering, or IPO) or in a later capital raise. After that, shares change hands between investors. When you buy on the NZX, your cash goes to another investor, not to the company. That second-hand trade is what most people mean by "the stock market".

Owning a share gives you three things:

• Price movement. If others later pay more for the company, your shares are worth more. They can also be worth less.
• Dividends. Many companies pay part of their profit to shareholders, though the board decides whether and how much.
• A vote. Shareholders elect the directors at the annual meeting.

How the stock market works in New Zealand: who does what

A market needs a venue, rules and people who connect buyers with sellers. In New Zealand, the roles are clearly split.

Many New Zealanders already own shares without placing a single trade. Most KiwiSaver funds invest part of their members' money in shares, here and overseas, so when markets fall, a growth fund balance usually falls with them. That link alone is a reason to understand how prices are made.

How share prices are set: the order book

Every listed share has an order book: a live list of buyers' bids and sellers' offers. A trade happens only when a bid and an offer meet. The gap between the best bid and the best offer is called the spread.

Take a fictional company, Harbour Fresh, on a quiet afternoon:

The spread is 4 cents ($2.52 minus $2.48). Now you place a market order to buy 700 shares. It takes the 400 offered at $2.52 ($1,008) and 300 of the 600 at $2.53 ($759). You pay $1,767 in total, an average of about $2.524 a share, before brokerage. The last traded price is now $2.53.

One modest order moved the price by a cent. That is the whole engine of the market. Prices rise when buyers are keener than sellers and fall when the reverse is true. A limit order works differently. Bid $2.50 and you join the queue as the best buyer, then wait for a seller to come to you.

From tap to ownership, the sequence runs like this:

1. You choose the share, the quantity and the order type in your broker's app.
2. The broker sends the order to the NZX.
3. The exchange matches it against the best opposite orders in the book.
4. The trade is confirmed and the last price updates for everyone.
5. Settlement follows a couple of business days later: cash moves, and the shares are recorded in your name or held for you by the platform's custodian.

Why share prices move

A share price is a collective estimate of a company's future profits. When the estimate changes, the price changes. The usual triggers:

• Results and guidance. A profit above expectations can lift a share; a cut to earnings guidance can sink it in minutes.
• Company news. A new contract, a chief executive leaving, a capital raise.
• Interest rates. When rates rise, term deposits look more attractive and future profits are worth less in today's money, which tends to weigh on shares.
• Large orders. A fund selling a big holding can push a price down even when nothing about the company has changed.
• Mood. Fear and enthusiasm spread, and prices often overshoot in both directions.

Companies listed on the NZX must tell the market promptly about information that could move their share price, under continuous disclosure rules. That is why announcements land on the exchange first, and why results days can be so lively. Prices tend to absorb public news quickly, often before most people finish reading the headline. For a closer look at that reaction, see how news moves stock prices.

What is the NZX 50, and what does an index tell you?

An index is a scoreboard for a group of shares. New Zealand's headline measure is the S&P/NZX 50, which tracks 50 of the largest companies on the NZX Main Board. Bigger companies count for more, because the index is weighted by market value.

Weighting matters more than it sounds. Imagine a toy index of two companies: A is worth $9 billion and B is worth $1 billion. If A rises 2% and B falls 10%, the index rises 0.8% (90% of 2%, plus 10% of minus 10%). Holders of B had a bad day while the headline looked fine.

So "the market was up" says little about any single share. You can also buy a whole index through an exchange-traded fund (ETF), which spreads your money across every company in it. Because the NZX is a small market, many New Zealanders also hold Australian and US shares through the same platforms, which is one reason diversification matters so much for a Kiwi investor.

How New Zealanders usually start, and what it costs

There is no single way in. The common routes:

• KiwiSaver. Many working New Zealanders are already members; the main choices are the fund type and the provider.
• Managed funds and ETFs. A ready-made spread of shares in exchange for a management fee.
• Individual shares. Bought through an online broker or investment app, on the NZX or overseas.

Costs differ by route: brokerage per trade, currency fees on overseas shares and annual fund fees. Small fees compound over years, so compare them. Sorted, the free money guide run by Te Ara Ahunga Ora Retirement Commission, has tools to compare funds. The FMA publishes warnings about scams and unregistered firms, and any provider you use should appear on the Financial Service Providers Register. Tax depends on your situation and on how you invest; Inland Revenue has the official guidance.

Before any of that, it pays to see the mechanics in action. A market game such as WallThrone starts you with $25,000 of play money, charges a 0.05% commission on every trade and runs a news channel, Ticker TV, that moves prices, sometimes without warning. Its companies are fictional, so it teaches how markets behave, not which NZX shares to buy.

Frequently asked questions

WallThrone is a game played with play money on fictional companies; it is not a broker and offers no access to real markets. This guide is for education only and is not financial advice.