CH 6 Are financial markets efficient?
Why the EMH Does Not Imply That Financial Markets Are Efficient • A strong view of EMH states that (2)
(1) expectations are rational, and (2) prices are always correct and reflect market fundamentals.
Rationale Behind the Hypothesis -When an unexploited profit opportunity arises on a security
(so-called because, on average, people would be earning more than they should, given the characteristics of that security), investors will rush to buy until the price rises to the point that the returns are normal again.
To better understand expectations, we examine the efficient markets hypothesis.
- Framework for understanding what information is useful and what is not - However, we need to validate the hypothesis with real market data. The results are mixed, but generally supportive of the idea.
Evidence in Favor of Market Efficiency - Performance of Investment Analysts and Mutual Funds should not be able to consistently beat the market -Investment Dartboard
-The "Investment Dartboard" (stocks picked by throwing darts at a board vs. stocks picked by investment advisors) often beats investment managers.
Evidence Against Market Efficiency Excessive Volatility -Researchers have found that fluctuations in the S&P 500 stock index....
-could not be justified by the subsequent fluctuations in the dividends of the stocks making up this index.
Evidence Against Market Efficiency Mean Reversion -Hence stocks that have done poorly in the past are... -Newer data is....
-more likely to do well in the future because mean reversion indicates that there will be a predictable positive change in the future price, suggesting that stock prices are not a random walk. - Newer data is less conclusive; nevertheless, mean reversion remains controversial.
Evidence Against Market Efficiency Excessive Volatility -Other research finds that there are...
-smaller fluctuations in stock prices when stock markets are closed, which has produced a consensus that stock market prices appear to be driven by factors other than fundamentals.
Evidence in Favor of Market Efficiency Technical Analysis is the study past stock price data, searching for patterns such as trends and regular cycles, suggesting rules for when to buy and sell stocks -The EMH suggests that.... -The simplest way to understand why is to...
-technical analysis is a waste of time. -use the random- walk result that holds that past stock price data cannot help predict changes
Example 6.1: The Efficient Market Hypothesis Suppose that a share of Microsoft had a closing price yesterday of $90, but new information was announced after the market closed that caused a revision in the forecast of the price for next year to go to $120. If the annual equilibrium return on Microsoft is 15%, what does the efficient market hypothesis indicate the price will go to today when the market opens? (Assume that Microsoft pays no dividends.)
.15= Rof and R* 120= Poft+1 0.15 = ($120−Pt) /Pt .015 x Pt= 120- Pt Pt (1.15) =120 Then, Pt = $104.35
The Practicing Manager: Implications for Investing (4)
1. How valuable are published reports by investment advisors? 2. Should you be skeptical of hot tips? 3. Do stock prices always rise when there is good news? 4. Efficient Markets prescription for investor
Evidence on Efficient Market Hypothesis • Favorable Evidence (4)
1. Investment analysts and mutual funds don't beat the market 2. Stock prices reflect publicly available info: anticipated announcements don't affect stock price 3. Stock prices and exchange rates close to random walk; if predictions of Delta P big, Rof > R* ==> predictions of DeltaP small 4. Technical analysis does not outperform market
Why the EMH Does Not Imply That Financial Markets Are Efficient -This strong view has 3 important implications
1. One investment is just as good as any other (stock picking is pointless) 2. Prices reflect all information 3. Cost of capital can be determined from security prices, assisting in capital budgeting decisions
Evidence on Efficient Market Hypothesis -Unfavorable Evidence (6)
1. Small-firm effect: small firms have abnormally high returns 2. January effect: high returns in January 3. Market overreaction 4. Excessive volatility 5. Mean reversion 6. New information is not always immediately incorporated into stock prices
Evidence Against Market Efficiency Various theories have been developed to explain the small-firm effect, suggesting that it may be due to... (5)
1. rebalancing of portfolios by institutional investors, 2. tax issues, 3.low liquidity of small-firm stocks, 4. large information costs in evaluating small firms, or 5. an inappropriate measurement of risk for small-firm stocks
Case: What Do Stock Market Crashes Tell Us About the Efficient Market Hypothesis? Does any version of Efficient Markets Hypothesis (EMH) hold in light of sudden or dramatic market declines? Strong version EMH? Weaker version EMH?
A bubble is a situation in which the price of an asset differs from its fundamental market value - Can bubbles be rational? Role of behavioral finance
Efficient Market Hypothesis Rof = R* This equation tells us that... Financial economists state it more simply:
A security's price fully reflects all available information in an efficient market. -AKA Theory of efficient capital markets
Efficient Market Hypothesis Recall from Chapter 3 that the rate of return for any position is the sum of the capital gains (Pt+1 − Pt) plus any cash payments (C):
At the start of a period, the unknown element is the future price: Pt+1. -But, investors do have some expectation of that price, thus giving us an expected rate of return.
Implications for Investing 1. How valuable are published reports by investment advisors?
For the most part, recommendations from investment advisors cannot help us outperform the general market -especially if that information is readily and publicly available
Rationale Behind the Hypothesis -Why efficient market hypothesis makes sense
If Rof = -5% and R* = 10% then Rof< R* and investors will sell the security as it is a poor investment and drive the price down its current price relative to the expected future price, until Rof reaches the level of R*
Why the EMH Does Not Imply That Financial Markets Are Efficient -This strong view, however, is not what EMH really means.
It just means that prices are unpredictable, which is not as strong as stating that prices are correct.. -As the next slide suggests, the existence of market crashes and bubbles cast serious doubt on this stronger view.
Implications for Investing 3. Do stock prices always rise when there is good news?
NO. -In an efficient market, stock prices will respond to announcements only when the information being announced is new and unexpected. - So, if good news was expected (or as good as expected), there will be no stock price response. - And, if good news was unexpected (or not as good as expected), there will be a stock price response.
Case: Foreign Exchange Rates Could you make a bundle if you could predict Foreign exchange (FX) rates?
Of course. -EMH predicts, then, that FX rates should be unpredictable. -Oddly enough, that is exactly what empirical tests show—FX rates are not very predictable.
Evidence on Efficient Market Hypothesis -Unfavorable Evidence Overview
Reasonable starting point but not whole story
Evidence Against Market Efficiency Mean Reversion:
Some researchers have found that stocks with low returns today tend to have high returns in the future, and vice versa.
Random Walk -Two Tests
The movements of a variable whose future changes cannot be predicted because, given today's value, the variable is just as likely to fall as to rise Two Tests 1. See if changes in stock prices are systematically related to past changes 2. Examines the data to see if publicly available info other than past stock prices could have been used to predict changes
Implications for Investing 2. Should you be skeptical of hot tips? Part 1
YES. -The EMH indicates that you should be skeptical of hot tips since, if the stock market is efficient, it has already priced the hot tip stock so that its expected return will equal the equilibrium return. - Thus, the hot tip is not particularly valuable and will not enable you to earn an abnormally high return.
Evidence in Favor of Market Efficiency Do Stock Prices Reflect Publicly Available Information as the EMH predicts they will? - If information is already publicly available,...
a positive announcement about a company will not, on average, raise the price of its stock because this information is already reflected in the stock price.
Rationale Behind the Hypothesis In an efficient market,..
all unexploited profit opportunities will be eliminated. -Not every investor need be aware of every security and situation. -As long as a few keep their eyes open for unexploited profit opportunities, they will eliminate the profit opportunities that appear because in so doing, they make a profit.
Evidence Against Market Efficiency Market Overreaction: -This violates the EMH because...
an investor could earn abnormally high returns, on average, by buying a stock immediately after a poor earnings announcement and then selling it after a couple of weeks when it has risen back to normal levels.
Evidence Against Market Efficiency The Small-Firm Effect is an..
anomaly. -Many empirical studies have shown that small firms have earned abnormally high returns over long periods of time, even when the greater risk for these firms has been considered.
Implications for Investing 4. Efficient Markets prescription for investor -It is frequently a sensible strategy for a small investor, whose costs of managing a portfolio may be high relative to its size, to...
buy into a mutual fund rather than individual stocks. -Because the EMH indicates that no mutual fund can consistently outperform the market, an investor should not buy into one that has high management fees or that pays sales commissions to brokers but rather should purchase a no-load (commission-free) mutual fund that has low management fees.
Evidence Against Market Efficiency New Information Is Not Always Immediately Incorporated into Stock Prices -Instead, on average stock prices....
continue to rise for some time after the announcement of unexpectedly high profits, and they continue to fall after surprisingly low profit announcements.
Efficient Market Hypothesis Rof = R* This equation tells us that...
current prices in a financial market will be set so that the optimal forecast of a security's return using all available information equals the security's equilibrium return.
Evidence Against Market Efficiency The small-firm effect seems to have ____ in recent years.....
diminished in recent years but is still a challenge to the theory of efficient markets
Efficient Market Hypothesis The Efficient Market Hypothesis views the expectations as..
equal to optimal forecasts using all available information. -Assuming the market is in equilibrium, expected returns (Re) equal required returns. (R*) Re = R* -Put these ideas together: efficient market hypothesis Rof (optimal forecast) = R* (equilibrium return)
Evidence Against Market Efficiency -The January Effect is the tendency of stock prices to
experience an abnormal positive return in the month of January that is predictable and, hence, inconsistent with random-walk behavior
Evidence in Favor of Market Efficiency Do Stock Prices Reflect Publicly Available Information as the EMH predicts they will? - Early empirical evidence confirms:
favorable earnings announcements or announcements of stock splits (a division of a share of stock into multiple shares, which is usually followed by higher earnings) do not, on average, cause stock prices to rise.
Evidence Against Market Efficiency New Information Is Not Always Immediately Incorporated into Stock Prices - Although generally true, recent evidence suggests that,
inconsistent with the efficient market hypothesis, stock prices do not instantaneously adjust to profit announcements.
Evidence in Favor of Market Efficiency Performance of Investment Analysts and Mutual Funds should not be able to consistently beat the market - Investment strategies using...
inside information is the only "proven method" to beat the market. In the U.S., it is illegal to trade on such information, but that is not true in all countries.
Arbitrage
market participants eliminate unexploited profit opportunities 2 types 1. Pure arbitrage: elimination of unexploited profit opportunities involves no risk 2. The type we discuss where the arbitrageurs take on some risk -if Rof (optimal forecast)> R* (equilibrium return) then arbitrage occurs until the Rof is lowered
Mini-Case: Raj Rajaratnam • In the mid-2000s, Mr. Rajaratnam made
millions of dollars for himself and his investors by investing in firms on which he allegedly received inside information. -His strategy shows that you can profit from information that the market does not have. -But that strategy landed him in jail for insider trading.
Implications for Investing 4. Efficient Markets prescription for investor -Investors should not try to...
outguess the market by constantly buying and selling securities. This process does nothing but incur commissions costs on each trade.
Evidence in Favor of Market Efficiency Random-Walk Behavior of Stock Prices that is, future changes in stock prices should, for all practical purposes, be unpredictable - If stock is predicted to rise,...
people will buy to equilibrium level; if stock is predicted to fall, people will sell to equilibrium level (both in concert with EMH) - Thus, if stock prices were predictable, thereby causing the above behavior, price changes would be near zero, which has not been the case historically
Behavioral Finance Dissatisfaction with using the EMH to explain events like 1987's Black Monday gave rise to the new field of behavioral finance, in which concepts from...
psychology, sociology, and other social sciences are applied to understand the behavior of securities prices -EMH suggests that "smart money" would engage in short sales to combat overpriced securities, yet short sale volume is low, leading to behavior theories about "loss aversion" -Other behavior analysis points to investor overconfidence as perpetuating stock price bubbles
Implications for Investing 4. Efficient Markets prescription for investor -Instead, the investor should pursue a "buy and hold" strategy:
purchase stocks and hold them for long periods of time. -This will lead to the same returns, on average, but the investor's net profits will be higher because fewer brokerage commissions will have to be paid.
Evidence Against Market Efficiency Market Overreaction:
recent research suggests that stock prices may overreact to news announcements and that the pricing errors are corrected only slowly
Expectations are very important in our financial system. - Expectations of..
returns, risk, and liquidity impact asset demand - Inflationary expectations impact bond prices - Expectations not only affect our understanding of markets, but also how financial institutions operate.
Evidence Against Market Efficiency Market Overreaction -When corporations announce a major change in earnings,
say, a large decline, the stock price may overshoot, and after an initial large decline, it may rise back to more normal levels over a period of several weeks.
Evidence in Favor of Market Efficiency Technical Analysis is the study past stock price data, searching for patterns such as trends and regular cycles, suggesting rules for when to buy and sell stocks -Therefore, technical analysis, which relies on...
such data to produce its forecasts, cannot successfully predict changes in stock prices
Evidence Against Market Efficiency The January Effect -Although this explanation seems sensible, it does not explain why institutional investors such as private pension funds, which are not subject to income taxes, do not
take advantage of the abnormal returns in January and buy stocks in December, thus bidding up their price and eliminating the abnormal returns.
Evidence Against Market Efficiency The January Effect -Investors have an incentive to sell stocks before the end of the year in December because they can then...
take capital losses on their tax return and reduce their tax liability. -Then when the new year starts in January, they can repurchase the stocks, driving up their prices and producing abnormally high returns.
Evidence Against Market Efficiency Excessive Volatility:
the stock market appears to display excessive volatility; that is, fluctuations in stock prices may be much greater than is warranted by fluctuations in their fundamental value.
Implications for Investing 2. Should you be skeptical of hot tips? Part 2 -As soon as the info hits the street,
the unexploited profit opportunity it creates will be quickly eliminated. - The stock's price will already reflect the information, and you should expect to realize only the equilibrium return.
Evidence in Favor of Market Efficiency - Performance of Investment Analysts and Mutual Funds should not be able to consistently beat the market -Mutual funds not only do not outperform the market on average, but ...
when they are separated into groups according to whether they had the highest or lowest profits in a chosen period, the mutual funds that did well in the first period do not beat the market in the second period. -Having performed well in the past does not indicate that an investment advisor will perform well in the future.
