Efficient Market Hypothesis Summary
Efficient Market Hypothesis
Ob 1: What is meant by an efficient market?
• Efficiency can be defined under many context, for example, how efficient is a machinery will depend on how many inputs are required to produce a certain amount of output, the less input used, the more efficient the machinery is.
• A financial market is said to be efficient if asset respond to relevant information instantaneously (or promptly) and accurately so that no one is able to use information that is already known by the market to earn abnormal returns net of transaction costs and should not deviate from its fundamental true & fair price for a long period of time.
• By abnormal, it means the return net of transaction costs is more than justified by its level of risk. Abnormal profit cannot earned from trading based on information already known to the market.
• Since information arrives at the market at any time and the content can be good or bad, stock price movements are unpredictable & follow a random walk.
• Inefficient market occurs when security prices deviates from its fundamentals over a long period of time where investors can make money out of it.
• From time to time, market may be inefficient, but over a long period of time, market is mostly efficient and financial crisis are rare events.
• Market efficiency tests are regarded as a joint test for the validity of
- market efficiency (what type of information is commonly known by the market and already reflected by the asset prices) &
- asset pricing model used to compute expected return as a function of risk (what information is not yet reflected by the asset prices and waiting to be exploited by investors to earn an abnormal return beyond that suggested by an asset pricing model e.g. CAPM)
• Regulators want the market to be efficient.
• Investors also want the market to be efficient because they want to pay at a true & fair price for stocks at all times. However, investors at certain time may not want the market
Ob 1: What is meant by an efficient market?
• Efficiency can be defined under many context, for example, how efficient is a machinery will depend on how many inputs are required to produce a certain amount of output, the less input used, the more efficient the machinery is.
• A financial market is said to be efficient if asset respond to relevant information instantaneously (or promptly) and accurately so that no one is able to use information that is already known by the market to earn abnormal returns net of transaction costs and should not deviate from its fundamental true & fair price for a long period of time.
• By abnormal, it means the return net of transaction costs is more than justified by its level of risk. Abnormal profit cannot earned from trading based on information already known to the market.
• Since information arrives at the market at any time and the content can be good or bad, stock price movements are unpredictable & follow a random walk.
• Inefficient market occurs when security prices deviates from its fundamentals over a long period of time where investors can make money out of it.
• From time to time, market may be inefficient, but over a long period of time, market is mostly efficient and financial crisis are rare events.
• Market efficiency tests are regarded as a joint test for the validity of
- market efficiency (what type of information is commonly known by the market and already reflected by the asset prices) &
- asset pricing model used to compute expected return as a function of risk (what information is not yet reflected by the asset prices and waiting to be exploited by investors to earn an abnormal return beyond that suggested by an asset pricing model e.g. CAPM)
• Regulators want the market to be efficient.
• Investors also want the market to be efficient because they want to pay at a true & fair price for stocks at all times. However, investors at certain time may not want the market