What is a Stock?

A stock (also called a share or equity) represents partial ownership of a company. When a company issues stock, it divides itself into millions of small pieces and sells those pieces to the public. Each piece is one share.

If Apple has 15 billion shares outstanding and you own 100 shares, you own 100/15,000,000,000 of Apple — a tiny fraction, but real ownership nonetheless.

What owning stock entitles you to:

• A proportional claim on the company's assets and earnings
• Voting rights on major corporate decisions (one share = one vote, typically)
• Dividends, if the company chooses to distribute profits
• The ability to sell your shares to anyone else at any time

Stocks are not just pieces of paper or numbers on a screen — they represent actual ownership stakes in real businesses. When Apple profits, shareholders profit. When Apple struggles, shareholders feel it.

Two types of stock:

• Common stock — what most investors own; includes voting rights; last to be paid in bankruptcy
• Preferred stock — pays fixed dividends; priority over common stockholders; usually no voting rights

Why Companies Issue Stock

Companies issue stock primarily to raise capital — money to fund growth, pay off debt, or finance acquisitions — without having to repay it like a loan.

The IPO (Initial Public Offering): When a private company first sells shares to the public, it is called an IPO. The company works with investment banks to price and sell shares. The proceeds go directly to the company (primary market). After the IPO, investors trade shares among themselves (secondary market) — the company receives no proceeds from these trades.

Why go public?

• Access to large amounts of capital without repayment obligations
• Liquidity for early investors and employees holding stock options
• Currency for acquisitions (paying with stock instead of cash)
• Prestige and brand recognition

The cost of going public:

• Ongoing regulatory disclosure requirements (SEC filings)
• Quarterly earnings pressure from public shareholders
• Loss of control as ownership dilutes
• Significant legal and compliance costs

How Stock Exchanges Work

A stock exchange is a marketplace where buyers and sellers of stocks meet to execute trades. The two most important US exchanges are:

NYSE (New York Stock Exchange)

• Founded 1792; the world's largest stock exchange by market cap
• Home to most established companies (JPMorgan, ExxonMobil, Walmart)
• Uses a hybrid model: electronic trading plus designated market makers (DMMs) on the floor

NASDAQ

• Founded 1971; fully electronic from the start
• Home to most technology companies (Apple, Microsoft, Google, Meta)
• The name is an acronym: National Association of Securities Dealers Automated Quotations

How a trade executes:

1. You place a buy order through your broker (Fidelity, Schwab, Robinhood)
2. The broker routes your order to the exchange or a market maker
3. Your order is matched with a seller's order
4. The trade settles in T+1 (one business day after the trade)
5. Shares appear in your account; cash leaves

Order types:

• Market order — buy or sell immediately at the best available price
• Limit order — buy only at or below a specified price; sell only at or above
• Stop-loss order — automatically sells if price falls to a specified level

Major US Indices

A stock market index measures the performance of a group of stocks. Indices serve as benchmarks — they tell you whether the overall market is up or down.

S&P 500 The most important US equity benchmark. Tracks the 500 largest US public companies by market capitalization, covering approximately 80% of total US stock market value. Market-cap weighted — Apple and Microsoft move the index more than smaller members.

NASDAQ Composite Tracks all ~3,000 stocks listed on the NASDAQ exchange. Heavily weighted toward technology — Apple, Microsoft, Amazon, Meta, and Google together represent roughly 40% of the index.

Dow Jones Industrial Average (DJIA) The oldest US index, tracking just 30 large, established companies. Price-weighted — a stock priced at $400 moves the Dow more than a stock priced at $40, regardless of company size. Considered less representative than the S&P 500 but widely quoted as a headline number.

Russell 2000 Tracks 2,000 small-cap US companies. Used as a barometer for smaller businesses and domestic economic health — small caps tend to be more sensitive to US economic conditions than large multinationals.

How Stock Prices Are Determined

At its most basic level, stock prices are set by supply and demand. If more people want to buy a stock than sell it, the price rises. If more want to sell than buy, it falls.

But what drives those buy and sell decisions? Several forces:

Fundamental value Investors estimate what a company's future cash flows are worth today (discounted cash flow analysis). If the stock trades below this intrinsic value, fundamental investors buy; above it, they sell.

Earnings expectations Stock prices often move most dramatically around earnings reports. A company growing earnings faster than expected will see its price rise; slower growth drives it down.

Interest rates When interest rates rise, future corporate earnings are worth less today (they are discounted at a higher rate), which pushes stock prices lower. When rates fall, the reverse occurs. This is why the Federal Reserve's decisions move markets dramatically.

Sentiment and momentum In the short term, fear and greed drive significant price moves. Stocks can trade well above or below fundamental value for extended periods based purely on market psychology.

In the short run, the market is a voting machine — reflecting popularity. In the long run, it is a weighing machine — reflecting actual business value. This distinction, attributed to Benjamin Graham, is the foundation of value investing.

Bull vs Bear Markets

Bull market — a period of rising stock prices, typically defined as a 20%+ gain from a recent low. Bull markets are driven by economic expansion, rising corporate earnings, low unemployment, and investor optimism.

Bear market — a period of falling stock prices, defined as a 20%+ decline from a recent peak. Caused by recession fears, rising unemployment, tightening monetary policy, or financial crises.

Market corrections — a 10–20% decline — are normal and occur roughly once per year. They are not bear markets and typically recover within weeks or months.

Historical context: Since 1928, the S&P 500 has delivered an average annual return of approximately 10% (7% after inflation), despite weathering the Great Depression, World War II, multiple recessions, the 2008 financial crisis, and the 2020 pandemic crash.

Every bear market in history has eventually been followed by a new all-time high. Long-term investors who stayed invested through downturns consistently outperformed those who tried to time the market.

Market Participants

Understanding who is trading alongside you explains why markets move the way they do.

Retail investors — individuals like you and me, trading through brokerage accounts. Represent a growing share of daily volume (~20–25% of US market volume) but generally have less information and shorter time horizons than institutions.

Institutional investors — pension funds, mutual funds, insurance companies, and endowments managing trillions of dollars. They move markets with their size and drive most of the fundamental research.

Hedge funds — pooled investment vehicles using sophisticated strategies: long/short equity, arbitrage, macro bets. Known for high fees (2% management + 20% performance) and aggressive risk-taking.

Market makers — firms (like Citadel Securities, Virtu) that continuously quote buy and sell prices, providing liquidity to the market. They profit from the bid-ask spread.

High-frequency traders (HFT) — algorithmic traders executing thousands of trades per second, exploiting tiny price discrepancies across exchanges. Represent roughly 50% of daily US market volume.

Central banks — in some countries, central banks directly purchase stocks or ETFs (Bank of Japan owns 7%+ of the Japanese equity market). The US Federal Reserve does not buy stocks but its interest rate decisions profoundly influence equity prices.

How to Buy Your First Stock

Step 1: Choose a brokerage Open an account with a reputable broker. Leading options for US investors include:

• Fidelity — no commissions, excellent research, no account minimum
• Charles Schwab — no commissions, strong customer service
• Vanguard — ideal for long-term, buy-and-hold index investing
• Robinhood — simple mobile app, fractional shares available

Step 2: Fund your account Transfer money from your bank via ACH transfer (2–3 business days) or wire transfer (same day).

Step 3: Research before buying

• Read the company's most recent annual report (10-K) at sec.gov
• Understand the business model: how does it make money?
• Check valuation: is the P/E ratio reasonable for its growth rate?
• Know the risks: what could go wrong?

Step 4: Place your order Search the stock by ticker symbol, select buy, enter the number of shares or dollar amount, and choose a market or limit order. Review and confirm.

Step 5: Monitor, don't obsess Check your portfolio quarterly, not daily. Short-term price fluctuations are noise. What matters is whether the underlying business continues to grow over years.

The biggest mistake first-time investors make is treating stocks like lottery tickets — buying based on tips or social media hype without understanding what they own. Know the business before you buy the stock.

Key Takeaways

• A stock represents fractional ownership of a company — shareholders have a claim on its assets and earnings
• Companies issue stock through IPOs to raise capital without taking on debt
• The NYSE and NASDAQ are the two primary US exchanges where stocks are bought and sold, settling in T+1
• The S&P 500 is the most important US benchmark, tracking the 500 largest companies by market cap
• Stock prices are driven by supply and demand, earnings expectations, interest rates, and investor sentiment
• Bull markets (+20% from low) average ~4 years and +112% gains; bear markets average ~1 year and −35% losses
• Every bear market in history has eventually recovered to new all-time highs — time in the market beats timing the market
• Research a company's business model, financials, and valuation before buying any stock