How Financial Markets Work (Beginner Guide)

At a glance

Core idea: A price is the last agreement between one buyer and one seller
Main participants: Investors, speculators, hedgers, market makers, brokers
What moves price: Order flow: the urgency imbalance between buyers and sellers
Prerequisite knowledge: None

Key takeaways

A quoted price is not a valuation. It is the most recent transaction between two parties who disagreed about the future.
Prices move because orders arrive, not because news exists. News matters only insofar as it makes someone trade with urgency.
Every market has the same skeleton: an order book, a matching engine, liquidity providers, and rules about who may trade what.
You are always trading against someone with a different reason for the trade, and often with better information or faster technology.
Understanding market plumbing explains most trading costs, which is why it directly affects whether a strategy is profitable.

What a market actually is

A financial market is a place, now almost always a computer system, where people who want to own something meet people who want to stop owning it. The thing being traded may be part-ownership of a company (a share), a promise of future repayment (a bond), an obligation to deliver a commodity at a future date (a futures contract), one national currency priced in another (forex), or a digital token (crypto). The mechanics are nearly identical in all of them.

The market’s job is price discovery: continuously producing a number at which supply and demand momentarily balance. That number is not the true value of anything. It is the point where the most eager buyer and the most eager seller currently agree, and it updates every time someone is impatient enough to accept the other side’s terms.

Who is in the market and what they want

Participant	Primary motive	Typical horizon	Effect on you
Long-term investors and funds	Own assets for expected returns, match liabilities	Years	Provide steady demand, trade on rebalancing dates
Hedgers (companies, farmers, airlines)	Reduce an existing business risk	Months to years	Willing to lose money on the hedge, so they pay a premium
Speculators and traders	Profit from price change	Minutes to months	Your direct competition for the same moves
Market makers	Earn the spread by quoting both sides	Seconds	You usually buy from and sell to them
Arbitrageurs	Capture price differences between related instruments	Milliseconds to days	Keep related markets aligned, remove easy edges
Brokers	Earn commissions and routing revenue	n/a	Your access point; their fees are your cost

Market participants have incompatible goals, which is exactly why trades happen.

Notice that two of these groups are systematically willing to accept worse prices: hedgers, because avoiding risk is worth paying for, and forced sellers such as funds facing redemptions. Most durable trading strategies are, at bottom, ways of being reliably available when those groups need to trade.

How a price is set: the order book

Modern exchanges maintain an order book, a live list of every resting buy and sell order at each price. Buy orders are called bids, sell orders are called offers or asks. The highest bid and lowest ask define the current quote, and the gap between them is the bid-ask spread.

        BIDS (buyers)              ASKS (sellers)
   Size   Price               Price    Size
   1,200  50.12   <-- best    50.14    900    <-- best
   3,400  50.11               50.15  2,600
     800  50.10               50.16  1,100
   5,000  50.09               50.18  4,300

A simplified order book. The market is 50.12 bid, 50.14 ask, with a 2 cent spread.

If you send a market order to buy 500 shares, you take the best ask: you pay 50.14 and the ask size shrinks to 400. If you buy 2,000 shares, you consume all 900 at 50.14 and 1,100 at 50.15, and your average fill is worse than the quote you saw. That difference is slippage, and it is the main hidden cost of trading size in thin markets.

If instead you post a limit order to buy at 50.12, you join the queue of bids and wait. You may get a better price, or you may never be filled, which is a real cost when the market moves away without you. Every strategy implicitly chooses between these two costs, and short-horizon strategies live or die by that choice.

The main markets and how they differ

Market	What is traded	Hours	Leverage	Notable structure
Stocks	Ownership shares in companies	Exchange hours plus limited extended sessions	Typically 2:1 overnight in a margin account	Fragmented across many venues, PFOF for retail flow
ETFs	Baskets of assets in one ticker	Same as stocks	Same as stocks	Authorised participants create and redeem units to keep price near NAV
Futures	Standardised contracts for future delivery	Nearly 24 hours, 5 days a week	High, set by exchange margin	Centrally cleared, daily mark to market, contracts expire and must be rolled
Options	Rights to buy or sell at a set price	Exchange hours	Embedded in the contract	Price depends on volatility and time as well as the underlying
Forex	Currency pairs	24 hours, 5 days a week	Very high, often 30:1 or more	Decentralised dealer market, no single order book
Crypto	Digital assets and derivatives	24/7, no close	Very high on offshore venues	Many venues, fragmented liquidity, variable counterparty risk

The same strategy behaves differently in each venue because the plumbing differs.

What happens between clicking buy and owning the asset

1
You submit an order to your broker
The order specifies instrument, side, quantity, and type (market, limit, stop). Your broker checks you have the buying power and that the order passes risk limits.
2
The broker routes the order
It may go to a public exchange, to a wholesaler that pays for the flow, or to an internal pool. Routing decisions affect your fill quality more than most retail traders realise.
3
The matching engine pairs it
Exchanges match by price then time priority: the best price wins, and among equal prices the order that arrived first is filled first.
4
You receive a fill confirmation
The trade is now economically yours, with profit and loss moving in real time.
5
Clearing and settlement finish the job
A clearing house steps between buyer and seller to guarantee the trade, and ownership legally transfers on the settlement date, now typically one business day after the trade for US equities.

Why prices move, in order of importance

Order flow imbalance. Someone needs to trade a large size quickly. This explains most intraday movement and almost all of the moves that appear to have no news attached.
Changes in expectations. Earnings, economic data, and policy decisions shift what participants believe future cash flows or rates will be, which changes the price they will accept.
Changes in the discount rate. When interest rates rise, future cash flows are worth less today, which mechanically lowers the fair price of long-duration assets such as growth stocks and long bonds.
Positioning and leverage. Crowded positions unwind violently. Forced liquidations, margin calls, and stop clusters create moves far larger than the news that triggered them.
Liquidity conditions. The same order moves price much further at 3am, on a holiday, or during a crisis, because fewer participants are willing to take the other side.

What this means for your strategy

Your edge must survive the spread and the fees. Market structure is a tax on every idea, and the shorter your holding period, the heavier the tax.
Liquidity is a feature you choose. Trading thin instruments looks attractive because moves are larger, but the cost of entering and exiting frequently exceeds the extra opportunity.
Timing within the session matters. Spreads are widest at the open and in overnight sessions, and volume clusters near the open and close. See trading sessions.
You will occasionally be trading against someone who knows something. Position sizing, not cleverness, is the defence.

Next, learn how to read a price chart so you can see order flow summarised visually, then read order types so you control how your orders interact with the book.

Frequently asked questions

If every trade has a buyer and a seller, how can a price rise?

Volume always balances, but urgency does not. Price rises when buyers are willing to pay higher and higher prices to get filled immediately, consuming resting sell orders faster than sellers replace them. The number of shares bought always equals the number sold; what changes is which side is crossing the spread.

Who decides the opening price each day?

Most exchanges run an opening auction. Orders accumulate before the session and the exchange computes the single price that would execute the largest possible volume. That becomes the open. The same mechanism runs at the close, which is why closing auctions carry enormous volume for index funds.

Do retail traders move prices?

Individually, almost never in large-cap markets. Collectively, and especially in small-cap stocks, low-float names, and some crypto assets, retail order flow can dominate short-term price action. That concentration is also why those instruments are more prone to violent reversals.

What is the difference between an exchange and a broker?

An exchange operates the order book and matching engine; it is the venue. A broker is your account provider and gives you access to those venues, handling custody, margin, and reporting. You cannot trade directly on most exchanges without a broker or membership.

Are markets rigged against small traders?

Not rigged, but genuinely unequal. Professionals have faster data, lower costs, better information, and more capital. The response is to compete where those advantages matter least: longer holding periods, less crowded instruments, and disciplined risk control rather than speed.

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Educational use only. This guide explains how a strategy works. It is not investment advice, not a recommendation, and no result described here is a forecast. Test any approach on historical and out-of-sample data, size positions conservatively, and never risk money you cannot afford to lose.