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How to Read and Understand a Share Chart

Understand and learn about all the numbers you see on a share chart, from 'Mkt cap' to 'P/E ratio', as we explain everything you need to know, step-by-step
Updated 29 July 2025

If you’re new to investing, our guide explains the data presented in share charts. While a share chart isn't the only resource you should use, it will assist you in making a more informed investment decision about whether or not to buy shares in the company. In this guide, we cover:
Please note: The companies mentioned in this guide are illustrative only and in no way constitute financial advice. Investing is risky and you may lose up to all of your original investment.

​What's in a Share Chart?

Whether or not you’re using the NZX, Google Finance or Yahoo Finance, share charts have a similar look and feel to them - i.e. they all have a graph and numbers. While the graph shows the share price over time, the numbers are where the detail is. To understand what these mean, it’s best to work through an example, step by step.

Let’s look at Air New Zealand using Google Finance (as illustrated in the above chart). Its ticker symbol is AIR, which will be the same on any sharemarket tool you use (so you can look up its prices by entering in 'AIR' in Yahoo Finance, the NZX and more). In this example, we've used data from 1 May 2024 to explain the important numbers on the share chart.

Understanding a share trading graph NZ
Air New Zealand's share price as at 1 May 2024 (click to enlarge) - Source: Google Finance

Understanding the Elements of a Share Chart

​Open: This is the price the share first traded at when the sharemarket opened. For example, at 10:00am, the first trade occurred at a price of $0.545.

High: This is the highest price the share reached within the day. It changes multiple times per day, especially if the share is volatile. During the day, someone bought shares for $0.55 around 10:30am.

Low: The is the lowest price in the day, and like ‘High’, it can change multiple times per day. $0.54 trades occurred around 3pm to 5pm in this example.

Bid/Ask: Why Google Finance doesn't show this, many share platforms do. The bid is what buyers are willing to pay for a share, whereas the Ask is what sellers will be prepared to sell for. The price moves based on the laws of supply and demand; more demand for a share will cause it to rise etc.

Mkt cap: This stands for market capitalisation. It’s the current share price multiplied by the number of shares issued. As the share price rises, the Mkt cap increases as the company is worth more, and vice versa. Mkt cap is what determines the biggest companies in a sharemarket. For example, the NZX50 is the fifty largest shares by market capitalisation. If a share price falls from say $1 to 10 cents, the market capitalisation will fall by the same proportion.

P/E ratio: This stands for price over earnings ratio. To explain P/E ratio in detail, let’s take a simple example. If the share price is $10, and the company’s most recent earnings-per-share was $1, then the P/E ratio is 10. Earnings per share is the amount of net profit after tax each share earns. For example, if the net profit after tax was $10 million, and there were 10 million shares, then the EPS is $1 ($10 profit/10 million shares).
  • Generally, a high P/E ratio could mean that a company's stock is over-valued, or else that investors are expecting high growth rates in the future. An example of high P/E ratio companies are Fisher and Paykel Healthcare (P/E ratio around 60 as at May 2024) and Auckland Airport (P/E ratio 57). Both of these companies have been viewed as high-growth companies, meaning investors expect their profits to grow year after year going forward.
  • Many companies have no earnings or are loss-making. If this is the case, they won’t display a P/E ratio given there are no earnings to put in the denominator. Low P/E companies, for example, those between 1 and 7, may be distressed. For example, they may have had a profit in the past but had a business event that means they’re unlikely to be profitable in the future. Because of this, the share price has fallen. 
  • In the Air New Zealand example we see a P/E of 5.5. This reflects the fact that investors don’t have confidence in Air New Zealand being profitable in the near future. As the share price falls, so does the P/E ratio.

Div yield: This is the dividend yield which is a percentage measure of how much the company pays its investors in dividends based on today’s share price. The higher the dividend yield, the higher the return on your investment. It’s calculated from dividing the annual dividend by the share price.
  • For example, if a company declared a dividend of $1 per share and the share price is $10, then the Div yield would be 10%. In the case of Air New Zealand, there is no dividend yield. However, a dividend is a static number that only changes every six months (at the most). If the share price drops, then the Div yield rises. If no dividend is declared in the next earnings announcement, the Div yield number will be 0.
  • In Australia, many investors push companies to pay dividends even if they are short of cash and have to borrow later on. This arguably affects the long-term growth of the company if it's continuously paying out cash and borrowing rather than re-investing in productive assets. New Zealand investors don't tend to do this, but it is something to be aware of if you're investing in the ASX.
  • In summary, dividend yields are not something to base a share purchase on if the price is volatile. Historically, dividend yield shares have included property companies which consistently collected rents from tenants and paid out dividends to the investors, as well as infrastructure companies like Auckland Airport. 

Prev close: This is the price the share closed at the day before. In the Air New Zealand chart, it is $0.54. It’s not necessary the following day's opening price, as buyers may offer more or less than the closing price the following day. In this case, the share opened at $0.54. 

52-wk high and 52-week low: This is the lowest and highest price the share has closed at during the last year. It’s helpful so investors can compare its low and high-point with where it is currently priced. For example, if the 52-week low and high were $0.54 and $0.84 respectively, and the current price is $0.54, you’d be buying at they lowest point in its recent history.

​Understanding the price and graph

The current trading price is listed on the top underneath the ticker symbol. On this chart, Air New Zealand is currently trading at $0.54. The (-0.005) (-0.92%) listed to the right of the price indicates the dollar change and percent change since the previous day’s closing price, which was half a cent.

You can view different periods, with '1 day' the standard among the NZX, Google Finance etc. For further details, click on 5 days, 6 months, YTD (year to date), 1 year, 5 year and Max (which is all the price history since the share listed on the share market, or as much as Google Finance has for shares that pre-date Google). The charts help you see if the share is trending up or down, and at what rate.

Essential Non-Financial Considerations (and other important things to know)

It is arguable that many shares on the NZX are overvalued, but the lack of investment options in New Zealand does, in some cases, inflate certain companies' market value. To find the Xeros and avoid the Sky TVs, consider our tips that go beyond the share market charts and metrics:
  1. Be wary of companies always making positive announcements in the media without substantiating revenue numbers. This is sometimes an attempt to drum up interest in its share price so the existing shareholders can sell down. As yourself - is the company making money? Who are its customers? Does it operate in a competitive market? Most importantly - do you understand what it is selling?
  2. Be aware that making sales does not mean the business is sustainable. Many large companies have gone bankrupt due to lack of cash (and no one willing to loan them money) even if sales were consistent with prior periods.
  3. A smart investor believes the balance sheet gives a great insight into the health of a company. Looking at two items – the cash and retained earnings - provide particularly useful insights. If you see little cash and negative retained earnings, the company may be in trouble even if sales are ‘increasing’.
  4. Understand gross profit, gross margin and net profit. Our guide has more details on calculating how profitable the company really is.
  5. Look for 'smart' companies that have a unique selling point. Companies that have done exceptionally well on the NZX recently include A2 Milk and Xero. A2 Milk is consistently profitable given its dominance of A2 Milk and has a healthy bank balance with money to invest in marketing and expansion. Xero hasn’t been as profitable, but it has always had a strong bank account due to regular investment support. It also has a product that requires a continuous paid subscription for any business wanting to access their accounting system and data, which makes it an essential service.
  6. Avoid companies in declining industries. Companies that haven’t shined, and largely fallen off the chart include Sky TV and the little-known Snakk Media. Both made sales, and Sky TV has historically been profitable. The issue for Sky TV is that subscribers have moved away from paying a close to $1,000 a year for movies and entertainment channels to $150/year for Netflix while Sky was stuck with paying for expensive sports coverage rights. Snakk Media was a hyped-up marketing company that continued to make big losses on small revenue until it ran out of money and went bust. Anyone who invested when they believed it was going to be the next biggest thing lost money. The lesson is simple – invest in what you understand and are interested in, and you’ll likely get a lot more out of your investment journey. The best investors have a knack for ignoring hype, public relations and spin - instead, they focus on the numbers.
  7. Don't just buy shares because you want to invest in something. Choose carefully, and/or consider an index fund. New Zealand has few IPOs, meaning just like our housing market, there aren't too many new opportunities to buy into.
  8. Look for monopolies. The NZX has a number of solid income-producing companies that operate in near-monopoly conditions. If you avoid those in a crowded market, it’s possible to invest in shares that have real long-term value.
  9. Be aware of the alternatives to investing in New Zealand. If you’re interested in investing in the US markets, platforms like Hatch and Stake have around 3,000 listed companies available in every industry. There’s also a lot more data and market commentary with hundreds of US shares given their high profile. While you probably won’t know ‘Eversource Energy’ as well as Contact Energy, or ‘Spirit Airlines’ as well as Air New Zealand, US markets have more liquidity (i.e. more money, more trades and more movement) than the NZX. The US markets give you the opportunity to invest in well-known companies like Facebook, Microsoft and Tesla. 

Final Thoughts

Knowing how to read a share chart will help you to determine if a company is a worthwhile investment. However it’s only one metric if you’re planning to invest for the long term. The best way to understand a company is to look at its annual report, analyse the financials and read market commentary around its performance and prospects. Always be cautious and don't rush into any investment decision. While shares make great investments if you get it right, many people get it wrong and lose money. To help ensure you're better informed, useful resources include:
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