Starting from zero · Course 2 of 11 · Before anything else
How a share actually trades
The four parties to one trade, what the quoted price is a price of, what settles and when, and the mechanics that can sell a position without you.
Most people who own shares have never been told what happened after they pressed the button. The order went somewhere, a price came back, and a position appeared. Each of those three steps involves a different firm, a different set of rules, and a different way of costing you money.
This course is the machinery. It is not about which companies to own. It is about what the quoted price actually is, who is standing on the other side of your order, and the handful of mechanisms that can move your position without you deciding anything.
Why plumbing is worth nine lessons
An investor who does not know this material makes four specific errors, and all four are avoidable.
The first is treating a quoted price as a fact about the company. It is not. It is an offer to trade a stated quantity, right now, and it says nothing about what the next thousand shares would cost.
The second is ignoring the spread. A round trip pays it twice, and in a thinly traded share it can cost more than a year of dividends.
The third is not knowing what an order type commits you to. A stop order is not a floor under your loss. It is an instruction to sell at whatever the market offers once a price is touched, and the two are different on the days it matters.
The fourth is the one that ends accounts. Margin, short interest and forced selling all share a property: the decision to close your position is taken by somebody else, on their schedule, at a price you did not choose.
The sequence
Lessons one to five are the trade itself. Who the parties are, what the order book shows, which order type to use, what the spread costs as a percentage, and how a zero-commission broker is actually paid.
Lessons six to nine are what happens afterwards. Settlement and the three dates every corporate action depends on. How a short position is created and how it ends. What a split, a dividend and a distribution each do to your share count and to the price history you are looking at. And the margin call, computed to the price at which the position is sold.
What this course does not do
It does not tell you when to trade, which broker to use, or which venue is best. It contains no view on any security. Corporate action mechanics are described from a filing, and the filing is named.
Rules change. The standard settlement cycle in the United States moved to one business day after the trade date in May 2024, which shifted every date that hangs off settlement. Where a rule is cited here, it is cited by name so it can be checked against the regulator's current text rather than against this page.
Vocabulary, not a verdict
How a share actually trades is 9 lessons on what the words mean and how the mechanics behind them work: what you own, how a trade happens, what it costs you. That is the floor rather than the answer. This course cannot tell you whether anything you already own is worth holding, because it has read no filing of yours.
Related
- How a trade happens is the one-lesson version of this course, and the place to start if none of these words are familiar yet.
- Two sides of one event is the other half of the same story: what the company itself records, rather than what the market does around it.
- Methodology states how a price is stored here, and why a stored close is not a live quote.
See our methodology for how the product reads a filing and what it refuses to compute.