Ticker League

What is a stock — and why does anyone care?

Before anything else — charts, earnings, portfolios — you need one solid mental model. This lesson builds it from scratch. No prior knowledge needed, and no formula until you understand the idea behind it.

Reading time: 20 mins

Lesson 1 / 7

Imagine you own a pizza restaurant

It is busy. People love your pizza. But you have a problem: you want to open five more locations, and that costs money you do not have. You could borrow it — take a loan, pay it back with interest — or do something more interesting: sell pieces of the restaurant to other people.

You divide the restaurant into 1,000 equal pieces and keep 600 for yourself. You sell the other 400 to friends, family and strangers who believe in your pizza. They give you money today; in return they own a fraction of everything — the ovens, the brand, the future profits.

Those pieces of ownership are called shares. Issuing them publicly is called going public. And the place where people buy and sell them is the stock market.

Your 1,000-slice pizza restaurant

Each slice = 0.1% ownership. Click a piece to see what it entitles the holder to.

The key insight: when you buy a stock you are not betting on a number going up. You are buying a legal ownership stake in a real business — with real rights attached.
One sentence to remember
A stock is a small piece of a company. When you buy one, you become a part-owner of that business — however tiny your fraction.

Why would a company give away ownership?

Most beginners never ask this. Companies do not have to sell shares — they could borrow instead. So why give up ownership? There are four big reasons.

  • They get money without paying it back

    A loan must be repaid — with interest, on a schedule, regardless of how the business is doing. Equity is permanent capital: no repayment, no interest. The trade-off is giving up a slice of future profits.

  • They can raise far more than a bank would lend

    When Apple went public in 1980 it raised $101 million in a single day — more than any bank would have offered a four-year-old computer company. Public markets pool capital from millions of investors at once.

  • They turn employees and investors into partners

    Equity grants and stock options give employees a real stake in the upside. If the company succeeds, everyone wins together. That alignment of incentives is one of the most powerful motivational tools in business.

  • It is the ultimate exit for founders

    Building a company for a decade and then taking it public (an IPO) is how most founders convert years of work into liquid wealth.

How does a share get its price?

Here is what surprises most people: there is no formula that calculates the “correct” price of a stock. The price is simply whatever a willing buyer and a willing seller agree on right now.

But what makes buyers and sellers change their minds? Click each event below to see how it typically moves a stock's price — and why.

What moves a stock price?

Click each event to see its effect — and the logic behind it.

PZZA$142.00+0.0%

Pizza Co. · Hypothetical example

Click an event above to see how — and why — it moves the stock.
The key insight
Stock prices do not move because of what happened — they move because of what investors now believe will happen. A company that just reported record profits can still fall if investors expected even bigger profits. We explore this fully in Lesson 2.

What does owning one share of Apple actually mean?

A giant company is divided into billions of shares, so a single share is a vanishingly small slice — but it is a real one. Pick a company and a number of shares to see exactly what you would own, and what it would entitle you to.

Your ownership calculator

Pick a company and a number of shares to see what you would own.

Your ownership stake

< 0.0001%

Your ownership of Apple

$210.00

Invested at today's price

$25.72

Your share of annual revenue

0.000010

“Your” fractional employees

What makes a stock different from a bond, a savings account, or crypto?

You will hear about all of these. A quick map before Lesson 3 goes deeper:

Stock — what it is

  • Ownership of a business
  • Large potential upside — grows with the company
  • Can pay dividends (a share of profits)
  • Voting rights on major decisions (for most share classes)
  • Price can fall — even to zero if the company fails

Bond / savings — what it is

  • Lending money to a company or government
  • Fixed interest payments — predictable income
  • Repaid in full at maturity — unless the issuer defaults
  • Not risk-free — prices fall when interest rates rise
  • No ownership, no voting rights
  • Limited upside — you get back what was promised
Quick note on crypto
Cryptocurrency is neither ownership nor a loan. It is a digital asset with no underlying business attached — for most coins, its value is driven largely by what buyers and sellers agree it is worth. High potential upside, high potential downside.

The number that makes it real

The companies listed on stock exchanges are almost incomprehensibly large. The total market value of a company's shares — the price of all of them combined — is its market capitalization. Use the slider to explore the scale of the businesses you can buy a piece of, starting from a single share.

Market capitalization explorer

$5.0T

NVIDIA's market cap — the company that makes modern AI possible

The largest company shown here

NVIDIA was worth about $300B in 2022. Within a few years it multiplied many times over — among the fastest wealth creation in market history.

Now play: Higher or Lower — Market Caps

Test your intuition: is Company A worth more or less than Company B? The surprise is the lesson sticking.

Play Higher or Lower

Frequently asked questions