What does a trade really cost?

"Zero-commission trading" is everywhere. And yet trading is never entirely free. Let's put every cost on the table before your first real trade — the opposite of how most people learn them.

The visible and the invisible

• Commission. What the broker charges per trade. Often $0 for US stocks nowadays; often NOT zero elsewhere or for other instruments. Always listed in the broker's fee schedule.
• The spread. From the previous lesson: buy at the ask, sell at the bid — the gap is a cost you pay the market itself, even at "zero commission."
• Currency conversion. Buying a US stock from a euro account? The conversion has its own fee, often larger than any commission.
• Regulatory & exchange micro-fees. Fractions of a cent baked into fills — tiny, but they exist; you'll see them on statements.
• Taxes. Profits and dividends are typically taxable, with rules that differ by country. Not a broker fee — but the largest "cost" many investors ever pay, so it belongs on this list from day one.

One more line for the cost list, and it begins with a box on the account form. A cash account lets you buy with the money you deposited. A margin account also lets you borrow from the broker against your holdings, and the app shows the borrowed part as extra buying power rather than as a loan. Two things follow. The broker charges interest on the borrowed amount daily. And a fall in the shares comes out of your money first: with half the position borrowed, a 20% drop in the stock is a 40% drop in what you own, and below a set level the broker sells your shares to protect its loan. Every loss figure in this course assumes a cash account.

Settlement: when is a share truly yours?

You press buy on Tuesday, the app instantly shows the share — but legal ownership transfers slightly later. This is settlement: the plumbing that moves cash one way and the share the other. In US markets it takes one business day (T+1); many other markets use T+2. In practice you'll barely notice — until the first time you try to withdraw cash from a just-sold position and meet the settlement clock.

Why we're telling you this now

Hidden costs discovered after the first trade create the classic beginner feeling of "the game is rigged." It isn't — it's just a machine with a price list, and now you have the whole list.

Try it now

1. Take the spread you measured last lesson, or read it again below: the bid against the ask for Apple.

2. Estimate the full round trip at zero commission: you buy at the ask and sell at the bid, so the spread is paid once, plus any currency conversion your account would need. Add them up.
3. Express the total as a percentage of the last trade price. That is the real price of a "free" trade.
4. Now do the same for the second row of that table, a thinly traded name. The commission is identical — zero — and the cost is not. Keep that number in mind whenever you hear "free trading": small, real, and worth knowing exactly. Five more companies of that size, from a screen for market caps under half a billion dollars, are below.