1.1 What You're Actually Buying
Understand what a stock actually represents before trading one.
Layer 1: Market Plumbing — Chapter 1 Goal: Understand what a stock actually represents before trading one.
The Core Idea
A stock = a tiny ownership slice of a real business.
When you buy 1 share of AMD, you own 1/1.6 billionth of the company. You have a claim on its future profits and assets. You're not buying a chart — you're buying a fractional piece of a business.
Key Terms
Shares Outstanding
Total shares the company has issued. AMD has roughly 1.6 billion.
Float
Shares actually available for public trading — excludes insider holdings, locked-up shares, restricted shares.
Float < Shares Outstanding (usually).
Why it matters: Low float = more volatile. Less supply available means buying/selling pressure moves price more.
Market Cap
The market's valuation of the whole company.
Market Cap = Share Price × Shares Outstanding
Example: AMD at $200 × 1.6B shares = $320B market cap.
This is what the market currently thinks the entire company is worth.
Market Cap Categories
| Category | Range | Examples |
|---|---|---|
| Mega cap | >$200B | AAPL, MSFT, NVDA |
| Large cap | $10B–$200B | Most S&P 500 |
| Mid cap | $2B–$10B | — |
| Small cap | $300M–$2B | — |
| Micro cap | <$300M | Avoid as beginner |
| Nano cap | <$50M | Penny stock territory |
Rule for learning: Stick to large caps and mega caps. They're liquid, well-covered, and harder to manipulate.
Common vs. Preferred Stock
Common Stock
What you normally buy.
- Voting rights
- Last in line if company goes bankrupt
- Unlimited upside
- Dividends if declared (not guaranteed)
Preferred Stock
Hybrid of stock and bond.
- Fixed dividend
- No voting rights
- Paid before common in bankruptcy
- Limited upside
- Rarely relevant for traders
Other Equity Wrappers You'll See
ETF (Exchange-Traded Fund)
A basket of stocks bundled into one ticker that trades like a stock.
- SPY → S&P 500 (top 500 US companies)
- QQQ → Nasdaq 100 (tech-heavy)
- IWM → Russell 2000 (small caps)
- XLK, XLF, XLE... → Sector ETFs
ETFs are how you get instant diversification with one click.
ADR (American Depositary Receipt)
A foreign company's stock wrapped for US trading.
- BABA → Alibaba (China)
- TSM → Taiwan Semiconductor
- NVO → Novo Nordisk (Denmark)
REIT (Real Estate Investment Trust)
A real estate company structured for tax efficiency. Required to pay out 90%+ of income as dividends.
- High dividend yield
- Sensitive to interest rates
Why Prices Exist at All (Price Discovery)
Every second, buyers and sellers disagree on value.
Price is just the most recent point where one buyer and one seller agreed.
Tomorrow's price reflects tomorrow's information and tomorrow's emotions. It's not "the right price" — it's "the cleared price right now."
This is a critical mental shift:
- Price is not value
- Price is not truth
- Price is the current equilibrium of supply and demand
What Actually Drives Stock Prices
Long-term (months to years)
- Earnings growth — the company makes more money
- Multiple expansion — the market is willing to pay more per dollar of earnings
That's it. Long-term, stocks follow earnings.
Short-term (minutes to weeks)
- Sentiment
- Order flow
- News reactions
- Technical levels
- Options positioning
- Noise
The further out you zoom, the more fundamentals matter. The closer in, the more flows and psychology matter.
Practical Takeaways
-
Stick to $10B+ market cap stocks while learning. Better liquidity, cleaner price action, harder to manipulate.
-
Avoid micro caps and low-float stocks. Manipulation, gaps, bad fills, and pump-and-dump schemes live here.
-
When you see a stock move 16% in a day (like the AMD move that frustrated you originally), ask:
- Did its market cap just grow $50B?
- Did anything fundamentally justify that?
- Or is this sentiment/flows/short squeeze?
-
Know what you own. Before trading any stock, you should know:
- What does this company do?
- What's its market cap?
- What's its float?
- Why might it move today?
Quick Self-Check
Before moving to 1.2, you should be able to answer:
- What does owning a share of stock actually mean?
- What's the difference between shares outstanding and float?
- How do you calculate market cap?
- What's the difference between an ETF and an individual stock?
- What's the difference between common and preferred stock?
- What drives prices long-term vs. short-term?