Last lesson you owned 10% of a food truck. Suppose you want out — who buys your slice? You'd have to find a buyer yourself and haggle. Painful.
The stock market solves exactly that problem, at scale. It's a giant, organized farmer's market where the thing being sold is ownership slices. The big U.S. marketplaces are called exchanges — you've heard of them: the New York Stock Exchange and the Nasdaq. Millions of buyers and sellers show up every weekday, so you can sell your Apple shares in seconds, because somebody out there wants them.
Where prices come from
Here's the thing nobody tells beginners: there's no committee setting prices. A stock's price is simply the last price a buyer and a seller agreed on. When you hear "Apple is at $230," it means someone just sold a share to someone else for $230. That's it.
So why do prices move every day?
Because people's opinions move. Every day, millions of people update their view of what a company is worth based on:
- News — a new product, a lawsuit, a factory fire.
- Results — the company reports how much it actually earned.
- Mood — plain old fear and greed, in both directions.
More buyers than sellers, price drifts up. More sellers than buyers, it drifts down. Multiply that by thousands of companies and you get the daily wiggle you see on the news.
Two takeaways to carry forward. First: daily moves are mostly opinion changes, not business changes — a company rarely becomes 3% worse by Tuesday. Second: when the news says "the market was up today," they're averaging lots of stocks together. How that averaging works — and what "SPY" means — is lesson 4. First, though: why bother with any of this?
Terms you now know
- Stock market — the organized marketplace for buying and selling shares.
- Exchange — a specific marketplace, like the NYSE or the Nasdaq.
- Market price — the last price a buyer and seller agreed on.
- Trading day — U.S. markets are open weekdays, roughly 9:30am–4pm Eastern.
Check yourself
Who decides that a share of Apple costs $230?
Nobody. $230 is just the most recent price a real buyer and a real seller agreed on. The next trade might be a few cents different.
A stock drops 2% today on no news. Did the company get 2% worse?
Almost certainly not. Daily moves mostly reflect shifting opinions and moods, not real changes in the business.