Financial Management · The nature and role of financial markets and institutions

Stock Exchanges and Market Efficiency for ACCA FM

Updated 11 October 2026 · Fact-checked

A stock exchange is a market where securities are issued (primary market) and traded between investors (secondary market). Market efficiency means share prices reflect available information. Weak form reflects past prices, semi-strong adds all public information, and strong form adds private information too. Match each form to the information in the question.

Understand Stock Exchanges and Market Efficiency

A financial market brings together people who want to raise money and people who want to invest. A stock exchange is a regulated market for shares and bonds.

The primary market is where a company sells new securities and receives the cash. Examples are an initial public offering, a rights issue and a new bond issue. The secondary market is where existing securities are traded between investors. The company gets no new cash from these trades. The price it sets still matters, because it affects the company's cost of capital and its ability to raise funds later.

A stock exchange performs several functions:

It lets companies raise new finance in the primary market.
It provides marketability and liquidity, so investors can sell shares quickly.
It gives a continuous price for shares, which is a basis for valuing the company.
It acts as a barometer of the economy and of investor confidence.
It supports regulation and disclosure, which protects investors and builds trust.
It helps with takeovers and with rewarding managers, for example through share options linked to the share price.

An efficient market is one where share prices fully and quickly reflect the relevant information. There are three forms. In the weak form, prices reflect all past price and trading data. Studying charts (technical analysis) cannot give consistent excess returns. In the semi-strong form, prices reflect all public information, including past prices, accounts and announcements. Analysing published information (fundamental analysis) cannot give consistent excess returns. In the strong form, prices reflect all information, public and private. Even insider information gives no advantage.

Each form includes the one before it. If a market is semi-strong efficient, it is also weak form efficient. In practice, major markets are generally regarded as at least weak form efficient and broadly semi-strong. Strong form efficiency is not generally supported, because insider dealing can be profitable, which is why it is illegal in many countries.

Key rules to remember

Weak form efficiency: Price reflects all past price and trading information; Technical analysis (chartism) cannot give consistent excess returns. Price changes follow a random walk.
Semi-strong form efficiency: Price reflects all publicly available information (includes weak form); Fundamental analysis cannot give consistent excess returns. Prices adjust quickly to new announcements.
Strong form efficiency: Price reflects all information, public and private (includes semi-strong); Even insiders cannot gain consistently. Evidence does not generally support this form.
Primary vs secondary market: Primary = new securities, cash goes to the issuer. Secondary = existing securities, cash goes to the selling investor; Use this test to classify any transaction in a question.
Implication of efficiency for managers: Share price = fair value given available information; Managers cannot fool the market with creative accounting. Timing of issues matters less. Wealth maximisation means making good investment decisions.

How to solve Stock Exchanges and Market Efficiency questions

Most questions ask you to classify a transaction, explain a function, or link information to a form of efficiency. Use this method.

1Read what the question asks: define, explain, classify, or discuss implications.
2For market type, ask who receives the cash. If the company receives new money, it is the primary market. If one investor pays another, it is the secondary market.
3For functions, list the points (finance, liquidity, pricing, barometer, regulation) and apply each to the scenario in the question.
4For efficiency, identify the information in the scenario: past prices, public news, or private information.
5Match the information to the form: past prices point to weak, public information to semi-strong, private information to strong.
6Remember the forms are cumulative. A market efficient in a higher form is also efficient in the lower forms.
7State the implication for the investor or manager, such as whether analysis or insider knowledge can beat the market.
8In a written answer, give a clear point, a short explanation and a link to the scenario.

Quickest way: Cash test and information test

When to use it: Use for Section A and Section B objective questions where you have about three minutes or less per question.

Primary or secondary? Ask: does the company get the cash? Yes means primary.
Efficiency form? Find the information the question says an investor uses.
Past prices only means the weak form is the one being tested.
Published accounts or news means semi-strong.
Inside or unpublished information means strong.
Pick the option that says that information cannot give consistent excess returns in that form, then check it does not contradict the cumulative rule.

Common mistakes in Stock Exchanges and Market Efficiency

Saying a share sale between two investors raises money for the company.
Students think any share trade is a fund-raising event.
Fix: Use the cash test. Only new issues put cash into the company. Secondary trades just change the owner.
Mixing up weak and semi-strong form.
Both mention information and the names are easy to swap.
Fix: Weak is past prices only. Semi-strong is all public information. Strong is all information including private.
Thinking forms are separate rather than cumulative.
Students treat the three forms as three different markets.
Fix: Remember each form includes the one before it. Semi-strong efficiency implies weak form efficiency.
Claiming efficiency means prices never fall or that every investor loses.
Efficiency is confused with prices being stable or investors being unable to profit.
Fix: Efficient prices can fall and rise. It means prices reflect available information and investors cannot gain consistent excess returns using that information.
Listing functions of a stock exchange without applying them.
Students memorise a list and write it out without context.
Fix: Tie each function to the case, for example liquidity for a shareholder who wants to sell, or a listing for a company that needs new capital.
Stating that markets are strong form efficient.
Students overstate the theory.
Fix: Say evidence supports weak form and broadly semi-strong form for major markets, but not strong form, as insider trading can be profitable.

Worked examples

Example 1

Classify each transaction as primary or secondary market: (a) Zeta plc issues 2 million new shares to raise cash for a new factory. (b) An investor sells 5,000 Zeta plc shares to another investor through the stock exchange. (c) Zeta plc makes a rights issue to existing shareholders.

Show the solution

Apply the cash test to each transaction.
(a) Zeta receives the cash from new shares, so this is the primary market.
(b) The buyer pays the selling investor. Zeta receives nothing, so this is the secondary market.
(c) A rights issue creates new shares and Zeta receives the cash, so this is the primary market.

Answer: (a) Primary. (b) Secondary. (c) Primary.

Example 2

An analyst studies Beta plc's share price chart for the last three years and uses the patterns to trade. She earns no more than the market average over several years. A second analyst studies Beta's published accounts and press releases and also earns no more than the average. A director trades on unpublished news of a contract and makes consistent gains. What does this suggest about the efficiency of the market in which Beta is traded?

Show the solution

The first analyst used past prices only. Earning no excess return suggests the market is weak form efficient.
The second analyst used public information. Earning no excess return suggests the market is semi-strong form efficient.
The director used private information and gained consistently. If this is true, prices do not reflect all information.
So the market is not strong form efficient.

Answer: The market appears weak and semi-strong form efficient but not strong form efficient, because insider information still gives consistent gains.

Exam tips

In objective questions, find the information type in the scenario first. It points directly to the form of efficiency.
In written answers, define each form in one line, then say what it means for analysis and for investors. This is easy to mark.
When asked about implications for managers, mention that prices reflect available information, so creative accounting will not fool the market and good investment decisions drive wealth.
Link stock exchange functions to the company in the scenario, such as liquidity or access to finance, rather than writing a generic list.
Do not claim strong form efficiency is proven. Say evidence is mixed and mostly supports the weak and semi-strong forms.

Practice questions from The nature and role of financial markets and institutions

Stock Exchanges and Market Efficiency in other exams

The same ground in other exams, if you are preparing for more than one or want another angle on it.

Stock Exchanges and Market Efficiency: frequently asked questions

What is the difference between the primary and secondary market?

The primary market is where new securities are issued and the issuer receives the cash. The secondary market is where existing securities are traded between investors, and the issuer receives nothing from the trade.

What are the three forms of the efficient market hypothesis?

The weak form says prices reflect all past price information. The semi-strong form says prices reflect all public information. The strong form says prices reflect all information, including private information.

Why does market efficiency matter to a financial manager?

If the market is efficient, the share price reflects the value of the company given available information. Managers cannot mislead investors with accounting presentation, and wealth is created by good investment and financing decisions.

What are the functions of a stock exchange in the ACCA FM exam?

Key functions are raising new finance, providing liquidity and marketability, setting share prices, acting as an economic barometer and providing regulation. Apply each point to the scenario to score well.