A share is a fractional ownership in a business. Everything else — multiples, indices, dividends, price movement — follows from that single idea. Start here.
Most investing mistakes trace back to a shaky understanding of what a share actually is. This primer covers the foundation: what you own when you own a stock, the basic metrics that describe it, the difference between what drives prices in the short term and what drives them in the long term, and how stocks build wealth over time. It is written for the serious beginner — the investor who wants the right mental model before buying anything.
01What is a share of stock?
A share is a legal claim to a fractional ownership of a business — its assets, its profits, and its voting rights. Own one share in a company that has 100 million shares outstanding, and you own one hundred-millionth of the business: its factories and cash, its earnings, and its votes at the annual meeting.
The practical meaning of that claim is simple. A business generates profit; the board decides what to do with it. You, as a shareholder, are entitled to your pro-rata portion of whatever the board returns — whether through dividends, share buybacks, or the compounding effect of profit retained and reinvested.
In the United States, there is no minimum share count — fractional shares are possible through most brokers. Many Asian exchanges (Singapore, Malaysia, Hong Kong) require a minimum lot of 100 or more shares per trade. This is a mechanical detail, not a philosophical one — but worth knowing before placing a first order.
02The metrics that describe a stock
Five numbers will carry you further than any chart. They are the shared language of every serious investor and the building blocks of every valuation framework.
Earnings per share (EPS)
EPS = Net Income ÷ Shares Outstanding
The company's profit, expressed per share. If a business earns $350 million and has 100 million shares, EPS is $3.50. EPS is the raw material from which dividends, buybacks, and reinvestment are funded.
Market capitalisation
Market Cap = Share Price × Shares Outstanding
The price the market is putting on the entire business. A $50 share price with 100 million shares outstanding means the company is valued at $5 billion — this is the number to compare across peers, not share price alone.
Price-to-earnings (P/E) ratio
P/E = Share Price ÷ EPS
How many years of current earnings the market is paying for one share. A P/E of 20 says the market is paying 20 years of this year's profit for a claim on the business — reasonable if earnings are growing; expensive if they aren't.
PEG ratio
PEG = P/E ÷ Earnings Growth Rate
Adjusts the P/E for the company's growth. PEG below 1 suggests the stock is cheap relative to growth; above 1 suggests the growth is already priced in. A P/E of 40 on 100% growth (PEG 0.4) is cheaper than a P/E of 10 on 5% growth (PEG 2).
Dividend yield
Yield = Dividends per share (12m) ÷ Share Price
The cash return to shareholders as a percentage of the current price. A $2 dividend on a $20 share is a 10% yield. Mature, slow-growing businesses tend to yield more; growth businesses tend to pay little or nothing and reinvest instead.
Book value & price-to-book (P/B)
P/B = Share Price ÷ Book Value per Share
For asset-heavy businesses — banks, insurers, holding companies — book value matters more than earnings. P/B below 1 means the market values the business at less than its accounting equity; above 1 means the market expects returns above the cost of capital.
03How a company returns capital to you
When a business generates earnings, management has three choices. Each reaches the shareholder differently, and understanding the mix tells you what kind of company you own.
- Dividends. Cash paid directly, usually quarterly or semi-annually. Mature businesses with limited reinvestment opportunities return more of their profit this way.
- Share buybacks. The company uses cash to retire its own shares, raising every remaining shareholder's claim on future earnings. Buybacks executed below intrinsic value create real per-share wealth; buybacks executed at all-time highs destroy it.
- Retained earnings reinvested. Profit left inside the business — used to build new capacity, develop new products, or acquire other businesses. Over a decade, this is often the largest source of return for growing companies, provided management allocates capital well.
For non-US residents, US stock capital gains are generally not taxable in the US, but US dividends are. Most brokers apply an automatic 30% withholding tax on US dividends paid to non-residents (reducible by treaty in some jurisdictions). This is a mechanical cost to factor into yield calculations.
04What drives share prices
The single most important distinction in investing is the difference between what moves prices in the short term and what moves them in the long term. Confuse the two and you will lose money in one timeframe while waiting for the other to arrive.
Emotion, flow, and noise
Price is set by demand and supply. In a short window, both are driven by:
- Sentiment — fear, greed, narrative
- News & headlines
- Forced liquidation and margin calls
- Index and ETF rebalancing
- Algorithmic and options-related flow
The same business can trade 20–50% higher or lower in four weeks without its intrinsic value changing at all.
Fundamentals, compounding, and value
Over multi-year horizons, share prices converge with what the business is actually worth. What drives that value:
- Earnings per share & free cash flow
- Future earnings growth
- Share buybacks & dividends
- Balance sheet quality
- Money supply & rates (slow-moving)
In the long run, the success of the business and the success of the stock are the same thing.
05Why expert predictions rarely help
A small industry exists to predict where the market is going next week. It almost never gets it right, and consuming its output makes investment decisions worse, not better. The mechanism is simple: the short-term direction of prices is driven by factors nobody can forecast reliably — sentiment, flows, and the arrival of new information — so the predictions reduce to educated guesses dressed up in confidence.
The useful framing is different. Successful long-term investing does not require predicting what the market will do in three months. It requires understanding what a business is worth, paying less than that, and waiting. The first part is learnable; the second is available to anyone willing to be patient.
For every confidently bearish headline in any given year, there is a bullish one from the same outlets weeks later — and vice versa. Reading both produces noise, not insight. The investor who ignores both and focuses on business fundamentals tends to do better over ten years than the one who reads all of them.
06Stock exchanges & indices
A stock exchange is the venue where shares trade. An index is a measurement — a weighted average of a selected basket of stocks, used as a proxy for a market or a segment of it. Most indices are either price-weighted (each stock's influence is proportional to its price) or capitalisation-weighted (proportional to its market cap).
| Region | Index | What it tracks |
|---|---|---|
| United States | S&P 500 | Cap-weighted average of 500 large-cap US stocks. The broadest benchmark for US equity. |
| Dow Jones Industrial (DJI) | Price-weighted average of 30 large US names. Historical importance, limited breadth. | |
| Nasdaq 100 (NDX) | Cap-weighted average of 100 large-cap, mostly technology, Nasdaq-listed stocks. | |
| Russell 2000 (RUT) | Cap-weighted average of 2,000 US small-cap stocks. The broad small-cap benchmark. | |
| United Kingdom | FTSE 100 | Cap-weighted average of the 100 largest stocks on the London Stock Exchange. |
| Europe | Euro Stoxx 50 | Cap-weighted average of 50 large-caps across 11 eurozone countries. |
| DAX · CAC | Frankfurt (40 stocks) and Paris (40 stocks) blue-chip indices. | |
| Asia | Nikkei 225 | Price-weighted average of 225 stocks listed on the Tokyo Stock Exchange. |
| Hang Seng · CSI 300 | Hong Kong (45 large-caps) and Mainland China (300 stocks) benchmarks. | |
| Straits Times Index (STI) | Cap-weighted average of 30 largest stocks on the Singapore Exchange. | |
| Oceania | S&P/ASX 200 | Cap-weighted average of 200 Australian-listed stocks. |
07How stocks build wealth
Returns to a shareholder come from two sources, which combine into what is usually called total return.
- Capital appreciation. The increase in share price over the holding period. If you buy at $320 and the stock trades at $502 a few years later, the $182 per share is capital appreciation.
- Dividends. Cash distributed from profits, typically paid quarterly or semi-annually. Over long holding periods, reinvested dividends have accounted for roughly a third to half of total equity return in major markets.
Growth-oriented businesses tend to pay little or nothing and reinvest instead — delivering return almost entirely through price appreciation. Mature, slow-growing businesses tend to return more cash directly. Neither approach is superior on its own; the right one depends on what the business can actually do with retained capital.
Over the 20 years to 2024, the S&P 500 total return (with dividends reinvested) compounded at roughly 10% per year — turning $100 into approximately $713. Over the 10 years to 2024, the figure was closer to 13% per year. These numbers include severe drawdowns; the return is the reward for sitting through them.
The mental model
- A share is fractional ownership of a business — not a ticker, not a price on a chart.
- Five metrics — EPS, P/E, PEG, market cap, dividend yield — describe any stock in the common language of the market.
- Management returns capital three ways: dividends, buybacks, and reinvestment. A sensible mix depends on what the business can earn on retained capital.
- Short-term price is driven by emotion and flow; long-term price is driven by fundamentals. Confuse the two and you lose money in both timeframes.
- Predicting short-term direction is not a skill; buying good businesses below fair value and being patient is.
- Indices are measurement tools, not portfolios. Know whether the one you benchmark against is price-weighted or cap-weighted, and what it actually holds.
- Total return = capital appreciation + dividends. Both are real; over long horizons, both matter.
This article is for informational and educational purposes only. It does not constitute investment, tax, or legal advice, nor a solicitation to buy or sell any security. Market statistics are illustrative and subject to revision. Tax treatment varies by jurisdiction and individual circumstance; consult a qualified professional. Past performance is not indicative of future results. Pinetree Capital does not accept responsibility for decisions made on the basis of this material.