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How the Stock Market Works: Exchanges, Orders, and Settlement
The stock market matches buyers and sellers of company shares. Here's how exchanges work, what happens when you place an order, and how trades settle.
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The stock market matches buyers and sellers of company shares. Here's how exchanges work, what happens when you place an order, and how trades settle.
This guide is designed for first-pass understanding. Start with core terms, then apply the framework in your own account workflow.
Billions of dollars change hands every single day on the stock market, yet most people who invest in it couldn't explain how it actually works. If you own stocks; or plan to — understanding the machinery behind the market will make you a more confident, less anxious investor. Let's pull back the curtain.
The stock market is a network of regulated exchanges where buyers and sellers trade ownership shares (equity) in publicly listed companies. When you place a buy order through a brokerage, it gets routed to an exchange or market maker, matched with a seller, and the trade settles one business day later (T+1). Prices are determined in real time by supply and demand; more buyers push prices up, more sellers push prices down.
The stock market is a network of exchanges where buyers and sellers trade shares of publicly listed companies. When you "buy a stock," you're purchasing a tiny ownership stake in a real business. That share entitles you to a proportional claim on the company's future profits and assets.
Think of the stock market like a massive, regulated auction house. Sellers list shares at prices they're willing to accept. Buyers bid at prices they're willing to pay. When a buyer's bid matches a seller's ask, a trade happens. This process repeats millions of times per day.
The modern stock market is a far cry from its early days. Today, high-frequency trading algorithms execute orders in microseconds, electronic networks span the globe, and retail investors can access the same markets as institutions through smartphone apps. The fundamental principle, however, remains unchanged: the stock market exists to facilitate the transfer of ownership in businesses from those who want to sell to those who want to buy.
In the US, two exchanges dominate: the New York Stock Exchange (NYSE) and the NASDAQ. While they serve the same basic purpose; matching buyers with sellers — they work differently under the hood.
The NYSE, founded in 1792, is the world's largest stock exchange by market capitalization. It still operates a physical trading floor on Wall Street, though most orders now flow electronically. The NYSE tends to list more established, blue-chip companies like Berkshire Hathaway, JPMorgan, and Johnson & Johnson.
The NASDAQ, founded in 1971, was the world's first fully electronic exchange. It's known for listing technology companies; Apple, Microsoft, Amazon, Google, and Meta all trade on NASDAQ. It has no physical trading floor; everything happens through computer networks.
Companies choose which exchange to list on based on listing fees, prestige, and their industry. But as an investor, it doesn't matter much. You can buy shares on either exchange through any standard brokerage account.
The stock market is a network of exchanges (NYSE, Nasdaq) where buyers and sellers trade shares of public companies. When you place a buy order, your broker routes it to the exchange where a market maker matches it with a seller. Prices are determined by supply and demand in real time.
T+1 means trades settle one business day after execution. When you buy stock on Monday, the shares are officially transferred to your account on Tuesday. Until then, the trade is pending. The SEC moved from T+2 to T+1 in May 2024 to reduce counterparty risk.
Payment for order flow (PFOF) is how commission-free brokers make money. Instead of routing your order to an exchange, they send it to a market maker (like Citadel Securities) who pays the broker for the privilege. The market maker profits from the bid-ask spread. Critics argue this may not get you the best execution price.
Try this workflow
Apply this concept with live balances, transactions, and portfolio data instead of static spreadsheets.
Graph: 4 outgoing / 4 incoming
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| Feature | NYSE | NASDAQ |
|---|---|---|
| Founded | 1792 | 1971 |
| Type | Hybrid (physical floor + electronic) | Fully electronic |
| Listed Companies | ~2,400 | ~3,300 |
| Known For | Blue chips, financials, industrials | Tech companies, growth stocks |
| Notable Listings | Berkshire Hathaway, JPMorgan, Walmart | Apple, Microsoft, Amazon, NVIDIA |
| Listing Fees | Higher | Lower |
Stocks don't just appear out of thin air. A company creates publicly tradeable shares through an Initial Public Offering (IPO). Here's how it works:
After the IPO, the company doesn't directly benefit when its stock price goes up (unless it sells more shares later). The daily trading is between investors, not between investors and the company.
Understanding the distinction between primary and secondary markets is key to grasping how the stock market functions. The primary market is where new securities are created and sold for the first time; IPOs happen here. Money flows directly to the company issuing shares.
The secondary market is where previously issued shares trade between investors. This is what most people mean when they say "the stock market." When you buy Apple stock on your brokerage app, you're buying from another investor on the secondary market, not from Apple itself. Apple got its money during the IPO; now shares just change hands between market participants.
Ever wonder who you're actually buying from when you place an order? Often, it's a market maker. Market makers are firms that commit to always having shares available to buy and sell. They provide liquidity; making sure you can trade whenever you want, not just when another individual investor happens to want the opposite side of your trade.
Market makers profit from the bid-ask spread. The "bid" is the highest price a buyer is willing to pay. The "ask" is the lowest price a seller is willing to accept. The difference between these two prices is the spread. For a heavily traded stock like Apple, the spread might be just one cent. For a thinly traded small-cap stock, it could be 10 cents or more.
When you place a market order (buy at whatever the current price is), you'll typically get filled at or near the ask price. This is one reason many experienced investors prefer limit orders — you set the exact price you're willing to pay, giving you more control over execution.
When you tap "buy" in your brokerage app, your order goes on a journey. It travels from your broker to either an exchange or a market maker. Many retail brokerages route orders to market makers like Citadel Securities or Virtu Financial, who fill the order and pay the broker a small fee for the privilege (this is called payment for order flow, or PFOF).
PFOF is how commission-free brokers like Robinhood make money. Critics argue that routing orders to market makers rather than exchanges may not always result in the best execution price for investors. The SEC has examined PFOF practices and continues to evaluate whether reforms are needed to ensure retail investors get fair pricing.
Once your trade executes, settlement happens; the actual transfer of shares and cash between parties. Since May 2024, the US stock market operates on T+1 settlement, meaning trades settle one business day after execution. Before 2024, it was T+2. This matters because you technically don't own the shares until settlement completes, and the cash isn't fully transferred until then either.
The US stock market is open Monday through Friday, 9:30 AM to 4:00 PM Eastern Time. It's closed on weekends and major holidays. That's just 6.5 hours of regular trading per day.
However, pre-market trading runs from 4:00 AM to 9:30 AM ET, and after-hours trading runs from 4:00 PM to 8:00 PM ET. Volume during these extended sessions is much lower, spreads are wider, and prices can be more volatile. Most individual investors stick to regular hours unless they need to react to earnings reports (which companies often release after the market closes or before it opens).
| Session | Hours (ET) | Volume | Best For |
|---|---|---|---|
| Pre-market | 4:00 AM – 9:30 AM | Low | Reacting to overnight news or earnings |
| Regular session | 9:30 AM – 4:00 PM | High | Most investors; best liquidity and spreads |
| After-hours | 4:00 PM – 8:00 PM | Low | Reacting to earnings releases |
Stock prices move for one fundamental reason: the balance between supply and demand shifts. More buyers than sellers? Price goes up. More sellers than buyers? Price goes down. But what causes those shifts?
There's a famous theory in finance called the Efficient Market Hypothesis (EMH). The simplified version: stock prices already reflect all available information, so you can't consistently beat the market through research or analysis because everything you know is already priced in.
The strong version of EMH says even insider information is reflected in prices (most people don't believe this). The weak version says past price patterns can't predict future prices (most evidence supports this; technical analysis doesn't reliably work).
In practice, the market isn't perfectly efficient, but it's efficient enough that most professional fund managers fail to beat a simple S&P 500 index fund over the long term. This is why index investing has become so popular; and it's the core insight behind the passive investing revolution started by Jack Bogle and Vanguard.
When people say "the market was up today," they're usually referring to a stock market index. An index tracks the performance of a specific group of stocks to represent the broader market or a segment of it.
The stock market serves several critical functions in the broader economy:
Participating in the stock market has never been easier. You need three things: a brokerage account, money to invest, and a plan. Most major brokerages; Fidelity, Schwab, Vanguard — charge zero commissions on stock and ETF trades. Many allow fractional shares, so you can buy $50 of a stock that costs $500 per share.
The most common ways individual investors participate:
The biggest advantage individual investors have over professionals is time. Hedge funds and mutual funds are judged quarterly. You can hold for decades, riding out every crash and correction. That patience is your edge.
A few things worth clearing up:
Understanding how the stock market works is the foundation for everything else in investing. Now that you know the mechanics; exchanges, IPOs, market makers, order flow, settlement, and what moves prices — you can make more informed decisions about where to put your money.
With Clarity, you can track your stock portfolio alongside your full financial picture — bank accounts, crypto, and more — all in one dashboard. Seeing how your investments fit into your overall net worth makes it easier to stay focused on the long game instead of reacting to daily market noise. Connect your brokerage accounts and get a real-time view of your holdings, performance, and allocation across every account.
This article is educational and does not constitute investment advice. Past performance does not guarantee future results. Consider consulting a financial advisor before making investment decisions.