What a Share Actually Is
When you buy a share in a company, you are not lending it money and you are not buying a product. You are acquiring a fractional ownership claim — a slice of the business itself. That slice entitles you to a proportional interest in the company's assets, its future earnings, and in the event of liquidation, whatever is left after all creditors are paid.
This ownership claim is not abstract. Shareholders have legal rights: the right to vote on major corporate decisions (electing the board of directors, approving mergers, changing the company's structure), the right to receive dividends if the company declares them, and the right to inspect certain financial records. Owning one share of a company with one billion shares outstanding makes you, in a literal sense, a 0.0000001% owner of that business.
The Origins of Equity Markets
The idea of pooling capital from many investors to fund a shared enterprise is ancient, but the formal equity market has a precise origin. The Dutch East India Company (Vereenigde Oost-Indische Compagnie, or VOC), founded in 1602, issued shares to the public on the Amsterdam Stock Exchange — the world's first formal stock exchange. The VOC needed enormous capital to fund long-distance trade voyages to Asia; no individual merchant could bear the risk alone. By selling shares, the company spread that risk across many investors, each of whom could then trade their shares with others.
This innovation — the tradeable, limited-liability share — transformed capitalism. It allowed large-scale enterprises to raise capital from people who would never set foot on a trading ship, and it gave those investors a way to exit their position without the company needing to repay them directly.
Primary and Secondary Markets
Equity markets operate in two distinct layers. In the primary market, a company issues new shares and receives the proceeds. The most visible form of this is an Initial Public Offering (IPO), when a private company lists on a stock exchange for the first time. Secondary share issuances also happen on the primary market.
Once shares are issued, they trade on the secondary market — the stock exchange itself. Here, existing shareholders sell to new buyers. The company receives no money from secondary-market transactions; all the proceeds go to the selling shareholder. When you buy Apple shares on the Nasdaq, you are buying from another investor, not from Apple.
Market Capitalisation
Market capitalisation (or "market cap") is the total market value of a company's outstanding shares: share price multiplied by the number of shares. A company trading at £20 per share with 500 million shares outstanding has a market cap of £10 billion. Market cap is the market's current best estimate of what the entire business is worth — a number that changes every second the market is open.
The Role of Stock Exchanges Today
Modern stock exchanges — the New York Stock Exchange (NYSE), Nasdaq, London Stock Exchange (LSE), and others — provide the infrastructure for price discovery, liquidity, and regulatory oversight. They set listing requirements (minimum size, financial disclosure standards, governance rules) that give investors some degree of protection. Electronic trading has made these markets extraordinarily fast and liquid: shares can be bought and sold in milliseconds, and bid-ask spreads on large companies are often fractions of a penny.