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Investing Basics
Understand a little. Practice once. Write your own plan. Each lesson explains an idea with an example, then asks you to answer a question and write a short reason before reading the explanation. Gather your thoughts as you learn, then follow the prompts to write your own learning or investment plan.
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02 · Stocks, ETFs, and indexes
What you’ll learn
Learn what stocks, ETFs, and indexes represent before comparing them.
Buying a stock gives you a small ownership share in a company. Its business performance matters, but its share price also reflects expectations and other factors. Using a company’s products does not mean you understand its profits or risks.
An ETF is a fund traded on an exchange and usually holds a collection of assets. An index is a measure calculated under a set of rules to track a group of assets. Some ETFs track indexes and others do not. The ETF label alone does not tell you how diversified a fund is.
See it in an example
Imagine two ETFs with different names that both invest heavily in the same technology companies. If those companies struggle, both funds may fall. Check the actual holdings, their weights, and the fund’s fees and risk disclosures to understand what you are researching.
Stock
- Plain meaning
- A stock represents part ownership in a company. Buying shares makes you a shareholder. You may benefit from a rising share price or dividends, but you can also lose money when the price falls; the company does not promise a fixed return.
- See it in an example
- Imagine a company with 10,000 shares, of which you own 100: that is 1% ownership. If the market price falls from 10 to 9 per share, your shares’ value falls from 1,000 to 900, before fees or dividends.
- When would I use this?
- When researching a company, separate liking its products from understanding the investment. Start with how it earns revenue, whether it makes a profit, and what could disrupt its business.
- Common misconception
- A familiar brand can still be a losing investment. Even a functioning business can see its share price fall when market expectations change.
ETF
- Plain meaning
- A fund pools investors’ money and invests toward a stated objective. An ETF is a fund whose shares trade on an exchange. One ETF share gives you a small interest in the fund, which may hold stocks, bonds, or other assets described in its disclosures.
- See it in an example
- Imagine two ETFs with different names that invest heavily in the same technology companies. Both could fall when those companies struggle. Their actual holdings tell you more than their names.
- When would I use this?
- In a fund’s disclosures, locate its objective, main holdings (the assets it owns), their weights, and its fees. Add anything unclear to your learning questions.
- Common misconception
- Owning an ETF does not automatically provide broad diversification. A fund focused on one sector can still be concentrated, and returns are not guaranteed.
Index
- Plain meaning
- An index combines the performance of a group of assets into one number under defined rules. Its constituents are the included assets; their weights determine how much each influences the index.
- See it in an example
- In a simplified index, company A has an 80% weight and B has 20%. If A rises 5% and B falls 5%, the weighted index rises 3%. A rising index can contain falling stocks.
- When would I use this?
- When you read that the market rose, check which index is being cited and which companies it covers. For an index-tracking fund, also examine the index rules.
- Common misconception
- An index is a measure, not something you buy directly. Products such as funds may track it, with their own costs and risks.
Use what you just learned to answer a question
Choose the answer you think fits and write a short reason in your own words. Then submit to see the answer and explanation and check your understanding.
Try this for yourself
Find a public ETF overview and locate its objective, main holdings, and fees. Add any unfamiliar terms to your plan as questions for your next study session.
03 · What a quote tells you
Explore further
Learning and research support; no personal trade instructions or guaranteed returns. · Version 2026-09-13.1