Market Efficiency Flashcards
What is an efficient market
a market where all relevant information currently available is fully reflected in the security prices instantaneously and in an unbiased way
What is a random walk
price changes are independent of one another/unpredictable
What are the assumptions of Market efficiency theory
- Rationality
2. Arbitrage theory
If it is not reasonable to assume investors will be rational, will market efficiency theory collapse because of the unrealistic assumption
No, because even if some investors are not rational, as long as their irrationally inspired trades are random the effects of their irrational actions would cancel each other out
What type of information is available for SFE
All relevant information
What type of information is available for SSFE
Public information (current and past)
What type of information is available for WFE
Past information
What is a feature and example of WFE
Future prices cannot be predicted based on analysis of past prices.
Current prices have already fully incorporated historical dividend records
What are the features and Example of SSFE
- Prices respond to information disclosure immediately
- If a market is efficient in ssf it must also be efficient in wf
Share prices react to a dividend increase as soon as a decision is announced
What are the features and example of SFE
- Prices react to new information as soon as it is generated rather than when it is publicly disclosed
- if a market is efficient in strong form it must be efficient in ssf and wf
Share prices react to a dividend increase as soon as the decision is made rather than when the decision is announced to the public
How is WFE tested?
- See if market prices follow a Random walk; if so then WFE may be accepted
- See if technical analysis can make abnormal returns; if so WFE may be rejected
What happens in reality if a market follows WFE
- Market prices do not follow any predictable pattern and therefore follow random walk
- Any forecast based on past price patterns is useless and therefore technical analysis is useless
What is the empirical evidence to prove random walk
T and T+1 are uncorrelated.
P=0 then it is uncorrelated.
What is technical analysis
Studies of historical prices using charts and other tools with the intention of discovering particular patterns of share price movements that appear to recur
TA What do they study
Historical price Movements