What happens when you buy a share

Most people's mental image of the sharemarket comes from film: shouting, screens, a line going up and down, someone losing everything in an afternoon. That image describes trading. It does not describe what a share is.

A share is a unit of ownership in a company. That is the entire definition, and everything else in this module follows from taking it literally.

The lawnmowing business

Suppose a small lawnmowing business is worth $100,000. It owns a mower, a trailer, a customer list and a name people in the suburb recognise. The owner wants to bring in partners, so the business is divided into 100 equal shares. Each share represents one hundredth of the business, so each is worth $1,000.

You buy one share for $1,000. What do you now own?

• 1% of the mower, the trailer, the customer list and the name.
• 1% of any profit the business chooses to distribute to its owners.
• 1% of the vote on decisions put to owners.
• 1% of whatever the business sells for, after its debts are paid, if it is ever sold.

Now the business has a good year and makes $20,000 of profit. The owners decide to distribute $10,000 of it and keep $10,000 in the business to buy a second mower. Your $1,000 share entitles you to 1% of the $10,000 distributed, which is $100. That payment is a dividend (a cash payment from a company you own part of): your share of profits that have actually been earned and actually been paid out.

The $10,000 that stayed in the business is not lost to you. It buys a second mower, the business can now serve more customers, and it is worth more than $100,000 as a result. Your 1% is now 1% of a bigger thing.

The two ways you can make money, and they are not mysterious

Both trace back to the same place. Not to another investor's loss. To a business selling something to a customer for more than it cost to provide. That is the point that connects this lesson to the riba lesson's distinction between trade and maysir (gaining at another's expense purely on the outcome of chance).

What changes when the business is listed

Scale up from the lawnmowing business to BHP and nothing about the structure changes. BHP is a much larger business, divided into a much larger number of shares, and those shares can be bought and sold on the Australian Securities Exchange rather than by ringing the owner. Owning one BHP share means owning a very small fraction of a mining company: its mines, its equipment, its contracts, and a matching fraction of the profits it distributes.

Listing adds two things and they are worth naming precisely.

• Liquidity (how quickly you can turn it into cash). A share in your neighbour's lawnmowing business is hard to sell. A share in BHP can be sold in seconds on any trading day.
• A visible price that moves constantly. The lawnmowing business is also changing in value every day, you simply cannot see it. Listing makes the change visible, which is genuinely useful and psychologically corrosive in roughly equal measure.

Why this matters for a Muslim investor specifically

Because the entire screening framework depends on this being literally true rather than a metaphor.

If a share were just a betting slip on a price, there would be nothing to screen. There would be no business, no revenue, no debt, no assets, just a number and a wager on it, which the riba lesson already dealt with. The reason you can ask whether a company's revenue comes from alcohol, or whether its debt exceeds 30% of its market value, is that you are buying a piece of that company and inherit a matching piece of its balance sheet and its activities.

That is the direct link into the Shariah-compliant vehicles module. The ASX Screener asks exactly these questions of every stock it covers, and the Methodology page sets out why each one is asked.

The practical takeaway

Once you take the definition literally, a cluster of questions that felt impossible become answerable. What does this business sell, to whom, and is that a good business? Is it making real profit? Is it carrying a dangerous amount of debt? Am I being asked to pay a sensible price for a share of it?

Those are questions about a business. The next lesson argues that for most people, the honest answer is that you will not out-analyse the market on them, and that there is a boring and well-evidenced way to sidestep the problem entirely.