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How the stock market works, shown with real filings.
Short lessons for people investing their own money. Every figure comes from what a company or fund filed, and you can check it yourself. Free, with no account.
- 01 What you own when you buy a share A share is a small slice of a real business. This lesson shows what that slice earned and paid in one year, using the figures Apple filed with the SEC.
- 02 How to read an income statement An income statement runs from what customers paid down to what was left for the owners. Here is every main line, using what Apple filed for the year to September 2025.
- 03 What a P/E ratio tells you, and what it hides The price-to-earnings ratio says how many dollars buyers pay for one dollar of a company's yearly profit. Here is how to work it out from a filing, and how it can mislead you.
- 04 What is inside an index fund A fund that tracks the S&P 500 holds about 500 companies, but not in equal amounts. Here is what one of the largest, VOO, actually held, from the report it files with the SEC.
- 05 Why a great track record can be luck Try enough strategies and one will look brilliant by chance. Here is the arithmetic, and the questions to ask before you trust a result someone shows you.
Heard a figure somewhere? Check it against the filing. These lessons explain how things work. They are not advice on what to buy or sell.