Module 25 min read

Stocks and ETFs

What each instrument actually is, how their risks differ, and two mechanics that routinely confuse beginners: splits and IPOs.

In summary

01A share is fractional ownership of a business; an ETF is a basket of them bought in one transaction.
02The difference that matters is not return, it is that a single company can go to zero and a broad index effectively cannot.
03A split changes nothing about what a company is worth. An IPO is the least informed moment at which you can buy one.

The two instruments

2.1A share is a slice of a business

Buy a share and you own a genuine fraction of a company — its assets, its brand, its contracts and its future profits. Own 100 shares of a company that has issued 100 million, and you own a millionth of it. Returns arrive two ways: the business grows its profits and the share reprices upward, or it distributes some of those profits as a dividend.

2.2An ETF is a basket in a single trade

An exchange-traded fund holds many companies at once. The most common kind simply tracks a published index — the S&P 500, or MSCI World — and makes no attempt to be clever. One purchase buys a sliver of hundreds or thousands of businesses, for one annual fee expressed as the total expense ratio.

Exhibit 1Single stock versus broad ETF

Dimension	Single stock	Broad ETF
What you own	One business	Hundreds or thousands
Company-specific risk	Full exposure	Almost entirely diversified away
Typical annual cost	Trading commission only	0.07%–0.25% of holdings
Realistic worst case	Total loss	A fall of 50% or more (−57% in 2007–09), recovered historically, sometimes over years
Research required	Ongoing, per company	Minimal
Return ceiling	Unbounded	The market’s return, less fees

Note: The last row is the honest trade-off: diversification removes the risk of ruin and, with it, the possibility of a single position transforming your outcome.

The table states it; the simulator below shows it. Move from one holding to five hundred and watch the quarterly swing collapse — then notice that it stops collapsing well before zero.

How many companies do you own?

Twelve quarters

Typical swing

23.4%

Worst quarter

-24.5%

Total loss risk

Real

One company means one management team, one product, one accident. Real — one company can go to zero — and no amount of research removes it.

The part worth internalising is not that diversification helps, but exactly which risks it removes, which it merely softens, and which it cannot touch at all.

1 of 50 right

An industryA shortage of one component halts production across the whole car industry.

Would owning 500 companies instead of one have protected you?Assume a broad index fund.

What this means for you

Diversification is the closest thing to a free lunch in investing — it lowers the risk of catastrophe without lowering expected return. That is why the site measures every single-stock idea against the index: an index costs nothing and needs no skill, so a stock pick has to beat it to have been worth the effort.

Check yourself

Why is a broad ETF usually the better first purchase?

Splits and IPOs

2.3A split changes the packaging, not the value

In a 10-for-1 split you receive ten shares for every one held, each worth a tenth as much. Your stake is identical. Companies do it to make the headline price look accessible, and it has no effect whatsoever on what the business is worth.

Exhibit 2A 10-for-1 split, before and after

	Before	After
Share price	€1,200	€120
Shares outstanding	100m	1,000m
Market capitalisation	€120bn	€120bn
Your 10 shares are worth	€12,000	€12,000

Note: A reverse split runs the other way — ten shares become one at ten times the price. It is often used to lift a share above an exchange’s minimum listing price, which makes it worth investigating rather than celebrating.

2.4An IPO is the least informed moment to buy

An initial public offering is the first sale of a company’s shares to the public. Three features make it structurally risky for a new investor.

Exhibit 3Why IPOs behave differently

Feature	What it means	Consequence
Short history	Often only two or three years of public accounts	Little evidence to judge management against
Seller advantage	Insiders choose the timing and the price	Sales are rarely timed for the buyer’s benefit
Lock-up expiry	Insiders may sell after roughly 90–180 days	A predictable wave of supply hits the price
Day-one pop	The price often jumps on the first day	Retail buyers typically pay after the jump, not before

Note: Studies of long-run IPO performance consistently find underperformance against the market over the first one to three years. Individual exceptions are famous precisely because they are exceptions.

What this means for you

Neither mechanic is a reason to avoid a company — but neither is a reason to buy one. If a split is the most interesting thing about an investment case, there is no investment case. And waiting two quarters after an IPO costs you very little and buys you real information.

Check yourself

A company you follow announces a 5-for-1 split. What has changed about the business?

Apply it

The Model Portfolio tab builds a risk-tiered pyramid — broad funds at the base, single names at the tip. It is this module expressed as a plan you can actually hold.

Model Portfolio

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