How investing actually works

Most explanations of investing start in the middle. They assume you already know what a share is, what an index does, and why anyone would leave money alone for twenty years. This one starts before that.

The whole thing rests on one idea: when you invest, you stop being a person with savings and start being an owner of something that does business. That is the entire difference between a savings account and an investment, and almost everything else follows from it.

What a share actually is

A company that wants money to grow with has two options. It can borrow, which means paying interest and eventually paying the money back. Or it can sell a slice of itself, which means giving up a share of everything it earns from then on, forever.

That second option is a share. Buy one and you own a genuine fraction of the business: its buildings, its brand, its contracts and its profits. Not a bet on the company, and not an IOU from it. A piece of it.

This is worth sitting with, because it explains something people find baffling — why share prices move at all. If you own a slice of a business, your slice is worth whatever people think that business is worth. And what people think a business is worth changes constantly, because businesses have good years and bad ones, and because the people doing the thinking are people.

The price of a share on any given morning is not a measurement of the company. It is the price at which the most optimistic buyer and the most pessimistic seller happened to agree. Over a day, that number is mostly mood. Over a decade, it tracks whether the business actually made money.

Where the returns come from

There are exactly two ways owning a share pays you, and it helps enormously to keep them separate in your head.

• The business grows. It earns more this year than last, so your slice is worth more than it was. This is where most long-term return comes from and it is desperately unexciting to watch.
• The business pays you. Some companies hand a portion of profits directly to owners each year. That payment is a dividend. It arrives as cash whether the share price went up, down or nowhere.

Notice what is not on that list: somebody else agreeing to pay more than you did. That is real, it happens, and it is also the part that has nothing to do with the business. If your entire reason for holding something is that you expect to sell it to a more enthusiastic person later, you are not investing in a company. You are forecasting a crowd.

Where your money goes when you buy

A detail that trips people up: when you buy a share, the company almost never receives your money. You are buying from another investor who wants out, at a price you both accept. The company got its money when the shares were first issued, possibly decades ago.

This is the difference between the primary market, where a company genuinely raises money by issuing new shares, and the secondary market, which is where essentially all of us operate — an enormous second-hand market in existing ownership slices.

It matters for one reason. A share price is not a scoreboard the company controls, and buying does not fund it. The price is simply where supply and demand met this morning. What you are entitled to is a share of future profits, and that entitlement is unaffected by what mood the market was in when you bought it.

The other half: bonds

Shares are one of the two things most portfolios hold. The other is bonds, and they work in the opposite direction.

Remember the company's two options at the start of this guide? A bond is the borrowing one. You lend money to a government or a company, they pay you interest at an agreed rate for an agreed period, and at the end they return the original amount. You are not an owner. You are a lender with a contract.

That contract is the whole point. If the business does spectacularly well, you still get exactly the interest you agreed to — no more. If it does badly, you still get paid, and if it collapses entirely, lenders are ahead of owners in the queue for whatever is left.

• Shares — unlimited upside, no promises, first to suffer when things go wrong.
• Bonds — capped return, a contractual promise, better protected if things collapse.

Bond prices still move, mostly because of interest rates: if newly issued bonds start paying more than yours, yours is worth less to anyone buying it second-hand. But the swings are usually gentler than shares, which is why a portfolio holding both tends to have a smoother ride than one holding only shares — and a lower long-run return to match. There is no free lunch in that trade, only a choice about how bumpy you want the journey.

Why doing nothing is not the safe option

The instinct that cash is safe and investing is risky is half right, and the missing half is the expensive part.

Cash cannot fall in nominal terms. A thousand pounds is a thousand pounds next year. What it cannot do is stay the same in real terms, because prices generally rise. If things cost more next year and your money did not grow, you can buy less with it. You have lost purchasing power without ever seeing a number go down.

This is inflation, and it is the reason "leave it in the bank" is not a neutral, risk-free decision. It is a decision with a slow, quiet, extremely reliable cost. Over a couple of years it is a nuisance. Over thirty, it is transformative.

So the real question is never "should I take a risk or not". Both options carry one. It is which risk suits the money: the visible, bumpy, historically well-compensated risk of owning businesses, or the invisible, smooth, uncompensated erosion of holding cash you did not need to hold.

First, the boring order of operations

Investing is not the first financial thing anyone should do, and any guide that skips this is doing you a disservice. Three things generally come first.

• Money you might need soon, kept somewhere it cannot fall. Cars break and jobs end. Without a buffer, the first emergency forces you to sell investments at whatever price happens to be available that week — which is the single most reliable way to turn a temporary drop into a permanent loss.
• Expensive debt. Paying off a debt charging a high rate is a guaranteed return equal to that rate. No investment offers a guaranteed anything. If your debt costs more than you could reasonably expect to earn, the maths is not close.
• Any free money on the table. An employer matching pension contributions is an immediate return on the matched portion, before anything is invested at all.

None of that is investing advice, it is arithmetic about which pound to use first. Once those are in hand, the rest of this series becomes relevant.

Why one share is a bad idea

Individual companies fail. Not usually, not often, but often enough that it matters — and the ones that fail rarely announce it in advance. Well-run businesses get overtaken. Entire industries get made obsolete by something nobody saw coming. A company can be genuinely excellent and still be worth less in ten years.

If your money is in one company and that happens, you do not get a partial refund for having done sensible research. You lose the money.

So investors spread out. Own a hundred companies and any one of them can fail without ruining you. Own a thousand and individual failures stop being events at all — they become a cost of doing business, absorbed by the rest. The technical word is diversification. The plain version: never let one bad outcome be the whole story.

Funds: how ordinary people own a thousand companies

Buying a thousand shares individually is impossible for a normal person. The fees alone would eat you, and the admin would take the rest of your life.

A fund solves this. Thousands of people put money into one pot, the pot buys shares in hundreds or thousands of companies, and each person owns a proportional slice of the whole pot. Put in a modest amount and you genuinely own a sliver of every company in it.

This is the single most useful invention in retail investing, and it is why the rest of these guides talk about funds rather than shares. Which fund, and what it costs you, are big enough questions to have guides of their own.

Compounding, and why everyone bangs on about it

Here is the part that does the heavy lifting, and the part that is genuinely hard to feel rather than merely understand.

When your investment grows, the growth joins the pile. Next year's growth is calculated on the bigger pile, including last year's growth. The year after, on a bigger pile still. Growth earns growth.

In the early years this is boring to the point of insulting. The numbers are small and nothing appears to be happening. What actually happens is that the curve is being loaded — and a curve that looks flat for a decade can look absurd at year thirty, without anything about it having changed.

£200 a month at a steady 5% a year. An illustration of the arithmetic only — no real market returns the same figure every year, and this is not a projection.

Read the last two rows again. The money more than doubles between year twenty and year thirty, and nothing changed — same contribution, same rate. All that happened was that a bigger pile grew for longer.

This is the mechanism behind the most repeated piece of advice in investing, which is that time in the market beats timing the market. It is not a slogan about patience being virtuous. It is arithmetic. The person who started ten years earlier and did nothing clever has an advantage the clever late starter cannot easily out-manoeuvre, because they are not competing on skill. They are competing on years.

How long is long term, actually?

"Invest for the long term" is said constantly and almost never quantified, which makes it useless as guidance.

A workable way to think about it: the shorter your horizon, the more your result is determined by luck about when you happened to start and stop. Stretch the horizon and the influence of any single bad stretch shrinks, because it is one period among many rather than the whole story.

That does not convert into a guarantee at any particular number of years, and anybody offering you one is overreaching. What it does give you is a sensible rule of thumb: money you need within a few years does not belong in something that can fall sharply, and money you genuinely will not touch for decades can tolerate a great deal of turbulence along the way.

The honest answer to "how long" is therefore not a number of years at all. It is: long enough that you will never be forced to sell at a moment you did not choose.

But should I just pick good companies?

Nearly everyone wonders this, so it deserves a straight answer rather than a lecture.

You can. People do. The difficulty is not identifying a good company — that part is often easy, and a company being excellent is usually well known. The difficulty is that its quality is already reflected in the price you have to pay. To profit from picking it, you need it to do better than everyone else already expects, which is a substantially harder thing to be right about.

You are also competing with people who do this full time, with better information and faster systems, and who are wrong often enough themselves to be humbling.

None of which makes it forbidden. A common compromise is to keep the great majority of your money in something broad and dull, and to run a small amount separately for the companies you want to back — sized so that being wrong is educational rather than expensive. That way curiosity does not get to endanger the part that matters.

What this means for a beginner

Three things follow from all of the above, and none of them are exciting.

• Starting matters more than optimising. The gap between a decent approach started now and a perfect approach started in three years is usually won by the decent one.
• Boring is a feature. Owning a slice of a large number of businesses and leaving it alone is not a failure of imagination. It is the thing that works.
• The plan has to survive you. A strategy you abandon in a bad month is worse than a duller one you actually keep. More on that in the guide on risk.

None of this requires you to predict anything, which is the good news, because nobody can.