شناخت ریسک و بازده ، CAPM و مدل سه عاملی فاما – فرنچ
شناخت ریسک و بازده ، CAPM و مدل سه عاملی فاما – فرنچ
ریسک و بازده:
مفهوم عمومی: انتظار بازده بالاتر داشتن مستلزم پذیرش ریسک بیشتر است.
بسیاری از سرمایه گذاران به این نکته توجه دارند که پذیرش ریسک بالاتر برای دریافت بازده های بالاتر الزامی است. در این مقاله ما دو مدل مهم را برای توضیح این رابطه بکار گرفته وآنها را توضیح می دهیم. آنگاه توضیح خواهیم داد که چگونه این ابزارها می توانند بوسیله سرمایه گذاران برای ارزیابی داراییهایی همانند اوراق قرضه مورد استفاده قرار گیرند.
چرا باید شرکتهای با ریسک بالاتر درآمدهای بالاتری هم داشته باشند ؟ مسلمً یک سرمایه گذار به ازای پذیرش ریسک بالاتر ، نیاز به بازده پیش بینی شده بالاتری دارد. و ما در واقع این ارتباط را با بررسی بازده های بلند مدت تاریخی سهام، اوراق قرضه و داراییهای با ریسک کمتر ، همانگونه که در اولین نمودار آمده است ، مشاهده می کنیم.
برای درک این مطلب ، فرض کنید که یک سرمایه گذاری که پیش بینی شده است یک میلیون دلار را بطور مستمر و سالانه ایجاد کند ، انجام گرفته است. یک فرد برای یک چنین دارایی چقدر حاضر است بپردازد؟ پاسخ به نامشخص بودن یا ریسک پذیری گردش وجوه نقد بستگی دارد. با مشخص بودن کامل شرایط که در آن گردش وجوهخ نقد بهنگام قرارداد کاملاض مشخص می شود ، یک سرمایه گذار دارایی را با نرخ بدون ریسک در نظر خواهد گرفت . همچنانکه میزان نا مشخصی افزایش می یابد ،بازده مورد نیاز برای جبران ریسک افزایش می یابد و در نتیجه در قیمت پایینتری سرمایه گذار مایل به سرمایه گذاری است ، زیرا ریسک بالاتر مستلزم دادن تخفیف است.
بعلاوه اقتصاد دانان فرض می کنند که سرمایه گذاران ریسک گریز هستند ، به این معنا که آنها حاضرند از بخشی از بازده چشم پوشی کنند ( و حتی حاضرند کمتر از ارزش فعلی بازده آتی پیش بینی شده را دریافت کنند ) تا ریسک را کاهش دهند. اگر این فرض درست باشد،انتظار داریم سرمایه گذاران برای جبران ریسک اضافی پذیرفته شده بواسطه نگهداری داراییهای ریسک پذیرتر ، بازده بیشتری را تقاضا کنند.
بی ثباتی شاخصی برای ریسک:
یکی از معیارهای کاملاً پذیرفته شده برای ریسک ، بی ثباتی ، یعنی میزان تغییر بازده دارایی در دوره های زمانی موفق ، است که عموماً به صورت انحراف استاندارد بازده ها بیان می شود. یک دارایی که دارای نوسانات شدید است ، انتظار میرود که دارای ریسک بالاتری باشد ، زیرا ارزش دارایی در زمانی که سرمایه گذار می خواهد آنرا بفروشد کمتر از آنچه است که پیش بینی شده بود. بعلاوه ، بی ثباتی بالاتر از نظر آماری، به معنی این است که ارزش آتی و بالقوه یک دارایی که بی ثباتی بالایی دارد در رنج وسیعتری افت می کند.
Understanding Risk and Return, the CAPM,
and the Fama-French Three-Factor Model
RISK AND RETURN
The General Concept: Higher Expected Returns Require Taking Higher Risk
Most investors are comfortable with the notion that taking higher levels of risk is necessary to
expect to earn higher returns. In this note, we explain two important models that have been
developed to make this relationship precise. Then we explain how such tools can be used by
investors to evaluate assets such as mutual funds.
Why should riskier companies have higher returns? Intuitively, an investor would require a
higher expected return in exchange for accepting greater risk. And, we do, in fact observe this
relationship when we look back at historical long-run returns of stocks, bonds, and less risky
securities as shown in the first chart.
To understand this, imagine an investment that is expected to generate $1 million per year in
perpetuity. How much is someone likely to pay for such an asset? The answer depends on the
uncertainty or riskiness of the cash flows. With complete certainty that the cash flows will all be
paid when promised, an investor would discount the asset at the risk-free rate. As the degree of
uncertainty increases, the return required to justify the risk will be much higher, resulting in a
much lower price the investor would be willing to pay, simply because of the higher required
discount rate.
Furthermore, economists have made the assumption that investors are risk-averse, meaning that
they are willing to sacrifice some return (and accept even less than the expected present value of
the future returns) to reduce risk. If this assumption is true, we would expect investors to
demand a higher return to justify the additional risk accepted by holders of riskier assets.
Understanding Risk and Return, the CAPM, and the Fama-French Three-Factor Model
Tuck School of Business at Dartmouth, Case 03-111 2
Volatility as a Proxy for Risk
One widely accepted measure of risk is volatility, the amount that an asset’s return varies
through successive time periods, and is most commonly quoted in terms of the standard
deviation of returns. An asset whose return fluctuates dramatically is perceived to have greater
risk because the asset’s value at the time when the investor wishes to sell it is less predictable. In
addition, greater volatility means that, from a statistical perspective, the potential future values of
more volatile assets span a much wider range.
Diversification and Systematic Risk
Although somewhat counterintuitive, an individual stock’s volatility in and of itself, is not the
most important consideration when assessing risk. Consider a situation in which an investor
could, without incurring additional cost, reduce the volatility associated with her portfolio of
assets. This is most commonly accomplished through diversification. Consider holding two
stocks that have the same expected returns, instead of one stock. Because stock returns will not
be perfectly correlated with each other, it is unlikely that both stocks will experience extreme
movements (positive or negative) simultaneously, effectively reducing volatility of the overall
portfolio. As long as assets do not move in lock step with one another (are less than perfectly
Historical Annual Returns
(1926-1999)
18.81%
5.36%
3.82% 3.17%
13.11%
Small Stocks
39.68%
Large Stocks
20.21%
LT Gov’t Bonds
8.12%
US T-Bills
3.29%
Inflation
4.46%
Source: Stocks, Bonds, Bills and Inflation 2002 Yearbook, 2002 Ibbotson Associates
StDev (σ)
Understanding Risk and Return, the CAPM, and the Fama-French Three-Factor Model
Tuck School of Business at Dartmouth, Case 03-111 3
positively correlated), overall volatility can be reduced, without lowering expected returns, by
spreading the same amount of money across the multiple assets.
This concept of diversification is one of the main tenets of modern portfolio theory – volatility is
reduced through the addition of more assets to a portfolio. It should be noted, however, that the
rate of volatility reduction from adding assets decreases as the number of assets in the portfolio
increases. As the chart below demonstrates for one potential scenario (20% volatility on each
asset and zero covariance between assets), the general rule of thumb is that a portfolio containing
30 or more assets is considered well-diversified.
Diversifying Reduces Portfolio Volatility
0%
5%
10%
15%
20%
25%
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40
Number of Securities in Portfolio
Portfolio Standard Deviation .
Volatility can be effectively reduced without significant cost by diversifying, so it makes sense
that investors should not be compensated for that portion of volatility which is merely stock
specific and has no impact on a well diversified portfolio. This type of volatility is called
unsystematic risk in the finance literature because it does not covary with the market as a whole,
but is merely the additional random “noise” present in that specific asset’s returns. Since this
random noise has an expected return of zero, it can be diversified away by adding more
securities to the portfolio. Its mean will be zero, and its standard deviation will be reduced as
more assets are added.
جهت خرید این مقاله کامل که در 23 صفحه ترجمه شده و به همراه متن اصلی می باشد .
شناخت ریسک و بازده ، CAPM و مدل سه عاملی فاما – فرنچ
شناخت ریسک و بازده ، CAPM و مدل سه عاملی فاما – فرنچ
ریسک و بازده:
مفهوم عمومی: انتظار بازده بالاتر داشتن مستلزم پذیرش ریسک بیشتر است.
بسیاری از سرمایه گذاران به این نکته توجه دارند که پذیرش ریسک بالاتر برای دریافت بازده های بالاتر الزامی است. در این مقاله ما دو مدل مهم را برای توضیح این رابطه بکار گرفته وآنها را توضیح می دهیم. آنگاه توضیح خواهیم داد که چگونه این ابزارها می توانند بوسیله سرمایه گذاران برای ارزیابی داراییهایی همانند اوراق قرضه مورد استفاده قرار گیرند.
چرا باید شرکتهای با ریسک بالاتر درآمدهای بالاتری هم داشته باشند ؟ مسلمً یک سرمایه گذار به ازای پذیرش ریسک بالاتر ، نیاز به بازده پیش بینی شده بالاتری دارد. و ما در واقع این ارتباط را با بررسی بازده های بلند مدت تاریخی سهام، اوراق قرضه و داراییهای با ریسک کمتر ، همانگونه که در اولین نمودار آمده است ، مشاهده می کنیم.
برای درک این مطلب ، فرض کنید که یک سرمایه گذاری که پیش بینی شده است یک میلیون دلار را بطور مستمر و سالانه ایجاد کند ، انجام گرفته است. یک فرد برای یک چنین دارایی چقدر حاضر است بپردازد؟ پاسخ به نامشخص بودن یا ریسک پذیری گردش وجوه نقد بستگی دارد. با مشخص بودن کامل شرایط که در آن گردش وجوهخ نقد بهنگام قرارداد کاملاض مشخص می شود ، یک سرمایه گذار دارایی را با نرخ بدون ریسک در نظر خواهد گرفت . همچنانکه میزان نا مشخصی افزایش می یابد ،بازده مورد نیاز برای جبران ریسک افزایش می یابد و در نتیجه در قیمت پایینتری سرمایه گذار مایل به سرمایه گذاری است ، زیرا ریسک بالاتر مستلزم دادن تخفیف است.
بعلاوه اقتصاد دانان فرض می کنند که سرمایه گذاران ریسک گریز هستند ، به این معنا که آنها حاضرند از بخشی از بازده چشم پوشی کنند ( و حتی حاضرند کمتر از ارزش فعلی بازده آتی پیش بینی شده را دریافت کنند ) تا ریسک را کاهش دهند. اگر این فرض درست باشد،انتظار داریم سرمایه گذاران برای جبران ریسک اضافی پذیرفته شده بواسطه نگهداری داراییهای ریسک پذیرتر ، بازده بیشتری را تقاضا کنند.
بی ثباتی شاخصی برای ریسک:
یکی از معیارهای کاملاً پذیرفته شده برای ریسک ، بی ثباتی ، یعنی میزان تغییر بازده دارایی در دوره های زمانی موفق ، است که عموماً به صورت انحراف استاندارد بازده ها بیان می شود. یک دارایی که دارای نوسانات شدید است ، انتظار میرود که دارای ریسک بالاتری باشد ، زیرا ارزش دارایی در زمانی که سرمایه گذار می خواهد آنرا بفروشد کمتر از آنچه است که پیش بینی شده بود. بعلاوه ، بی ثباتی بالاتر از نظر آماری، به معنی این است که ارزش آتی و بالقوه یک دارایی که بی ثباتی بالایی دارد در رنج وسیعتری افت می کند.
Understanding Risk and Return, the CAPM,
and the Fama-French Three-Factor Model
RISK AND RETURN
The General Concept: Higher Expected Returns Require Taking Higher Risk
Most investors are comfortable with the notion that taking higher levels of risk is necessary to
expect to earn higher returns. In this note, we explain two important models that have been
developed to make this relationship precise. Then we explain how such tools can be used by
investors to evaluate assets such as mutual funds.
Why should riskier companies have higher returns? Intuitively, an investor would require a
higher expected return in exchange for accepting greater risk. And, we do, in fact observe this
relationship when we look back at historical long-run returns of stocks, bonds, and less risky
securities as shown in the first chart.
To understand this, imagine an investment that is expected to generate $1 million per year in
perpetuity. How much is someone likely to pay for such an asset? The answer depends on the
uncertainty or riskiness of the cash flows. With complete certainty that the cash flows will all be
paid when promised, an investor would discount the asset at the risk-free rate. As the degree of
uncertainty increases, the return required to justify the risk will be much higher, resulting in a
much lower price the investor would be willing to pay, simply because of the higher required
discount rate.
Furthermore, economists have made the assumption that investors are risk-averse, meaning that
they are willing to sacrifice some return (and accept even less than the expected present value of
the future returns) to reduce risk. If this assumption is true, we would expect investors to
demand a higher return to justify the additional risk accepted by holders of riskier assets.
Understanding Risk and Return, the CAPM, and the Fama-French Three-Factor Model
Tuck School of Business at Dartmouth, Case 03-111 2
Volatility as a Proxy for Risk
One widely accepted measure of risk is volatility, the amount that an asset’s return varies
through successive time periods, and is most commonly quoted in terms of the standard
deviation of returns. An asset whose return fluctuates dramatically is perceived to have greater
risk because the asset’s value at the time when the investor wishes to sell it is less predictable. In
addition, greater volatility means that, from a statistical perspective, the potential future values of
more volatile assets span a much wider range.
Diversification and Systematic Risk
Although somewhat counterintuitive, an individual stock’s volatility in and of itself, is not the
most important consideration when assessing risk. Consider a situation in which an investor
could, without incurring additional cost, reduce the volatility associated with her portfolio of
assets. This is most commonly accomplished through diversification. Consider holding two
stocks that have the same expected returns, instead of one stock. Because stock returns will not
be perfectly correlated with each other, it is unlikely that both stocks will experience extreme
movements (positive or negative) simultaneously, effectively reducing volatility of the overall
portfolio. As long as assets do not move in lock step with one another (are less than perfectly
Historical Annual Returns
(1926-1999)
18.81%
5.36%
3.82% 3.17%
13.11%
Small Stocks
39.68%
Large Stocks
20.21%
LT Gov’t Bonds
8.12%
US T-Bills
3.29%
Inflation
4.46%
Source: Stocks, Bonds, Bills and Inflation 2002 Yearbook, 2002 Ibbotson Associates
StDev (σ)
Understanding Risk and Return, the CAPM, and the Fama-French Three-Factor Model
Tuck School of Business at Dartmouth, Case 03-111 3
positively correlated), overall volatility can be reduced, without lowering expected returns, by
spreading the same amount of money across the multiple assets.
This concept of diversification is one of the main tenets of modern portfolio theory – volatility is
reduced through the addition of more assets to a portfolio. It should be noted, however, that the
rate of volatility reduction from adding assets decreases as the number of assets in the portfolio
increases. As the chart below demonstrates for one potential scenario (20% volatility on each
asset and zero covariance between assets), the general rule of thumb is that a portfolio containing
30 or more assets is considered well-diversified.
Diversifying Reduces Portfolio Volatility
0%
5%
10%
15%
20%
25%
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40
Number of Securities in Portfolio
Portfolio Standard Deviation .
Volatility can be effectively reduced without significant cost by diversifying, so it makes sense
that investors should not be compensated for that portion of volatility which is merely stock
specific and has no impact on a well diversified portfolio. This type of volatility is called
unsystematic risk in the finance literature because it does not covary with the market as a whole,
but is merely the additional random “noise” present in that specific asset’s returns. Since this
random noise has an expected return of zero, it can be diversified away by adding more
securities to the portfolio. Its mean will be zero, and its standard deviation will be reduced as
more assets are added.
جهت خرید این مقاله کامل که در 23 صفحه ترجمه شده و به همراه متن اصلی می باشد .
ریسک سود مازاد، ارزش‌های ذاتی و قیمت‌های سهام:
از استفن پی باجینسکی و جیمز ام والن ـ
تحقیقات تجربی حسابداری شواهد نسبتاً کمی در مورد این که آیا از نظر ریسک ، اختلافات مقطعی سودی حسابداری با اختلافات مقطعی در قیمت‌های سهام، ارتباط دارند یا نه؟ ارائه می‌دهد. ما با توجه به ریسک یا خطر مربوط به ارقام حسابداری دو پرسش را مطرح می‌کنیم:
1 ـ آیا ارزیابی‌های خطر مربوط به حسابداری (یعنی خطر نظام مند و تغییر پذیری کل در مجموعه زمانی بهره مازاد حقوق صاحبان سهام شرکت) با ارزیابی بازار و برآورد خطر حقوق صاحبان سهام ارتباطی دارد یا نه؟
2 ـ اگر این چنین است، پس آیا این ارزیابی‌ها به صورت افزایشی با ارزشیابی بازار و ارزیابی خطر حقوق صاحبان سهام در ورای دیگر عوامل قابل بررسی و مشاهده، نظیر عوامل موجود در الگوی سه عامل French, Fama (1992) ارتباط دارند؟ ما بر مبنای یک معیار اساسی حسابداری در مورد ریسک قیمت بازار اختلاف میان قیمت واقعی سهام و الگوی ارزشیابی سود مازاد بر پایه برآورد ارزش سهام و با استفاده از نرخ بهره بد ون ریسک را ارزیابی می‌کنیم.
نتایج ما حاکی از آن است که هم ریسک سیستماتیک و هم مجموع تغییر پذیری در بهره مازاد حقوق صاحبان سهام به طور ناقص تفاوت قیمت گذاری را نشان می‌دهد، و تأثیر توضیحی مجموع تغییر پذیری به عوامل فاما و فرنچ ـ بقای بازار، اندازه شرکت و نسبت ارزش بازار به ارزش دفتری ـ افزوده می‌شود.
Fundamental valuation of equity shares requires estimation of expected future payoffs and the risk inherent in those
payoffs. Existing research on the usefulness of accounting earnings numbers has devoted far more attention to their role
as payoff-relevant information than to their role as risk-relevant information. One exception is the seminal Beaver et al.
(1970) study, which shows that accounting-based risk measures are positively associated with market model beta, but
which does not examine whether accounting-based risk measures explain share prices or returns. Thus far, the empirical
accounting research literature has surprisingly little to say about whether accounting earnings numbers capture
cross-sectional differences in risk that are associated with cross-sectional differences in share prices. In this study, we
investigate the risk-relevance of accounting numbers by addressing the question: Are accounting earnings-based risk
measures associated with the capital market’s assessment and pricing of firm risk? The answer to this question will inform
capital markets participants, as well as accounting researchers and teachers, about the fundamental usefulness of
accounting earnings numbers in assessing and pricing risk. The findings will also contribute to a better understanding of
how to specify accounting earnings-based valuation models, and how to use them in settings in which market-based risk
measures (e.g., market model beta) are not available.
We also address a second question: Are accounting earnings-based risk measures incrementally associated with the
market’s assessment and pricing of equity risk beyond other observable risk factors, such as the three factors in the Fama
and French (1992) model (market model beta, firm size, and book-to-market ratios)? Research by Fama and French
(1992) and others shows that the single factor capital asset pricing model may be incomplete because ad hoc factors
outside of the model (including factors based on accounting numbers, such as the book-to-market ratio) appear to explain
stock returns. Our investigation contributes evidence on whether accounting earnings-based risk measures capture
elements of priced risk that traditional measures of equity risk (e.g., market model beta) or factors identified by more
recent ad hoc approaches to risk (e.g., Fama and French 1992) do not capture.
Traditional theory on the role of accounting numbers in valuation, such as the residual income valuation models (e.g.,
Ohlson 1995; Feltham and Ohlson 1995), simplify the role of risk by assuming that investors are risk neutral and discount
rates are nonstochastic and flat. More recently, Feltham and Ohlson (1999) point out that equity values should price as
fundamental risk the nondiversifiable variability inherent in expected future residual income. Feltham and Ohlson (1999)
demonstrate analytically that (at least in principle) one can incorporate risk in residual income valuation by reducing
Accounting Review Jan 2003 v78 i1 p327(25) Page 1
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Residual income risk, intrinsic values, and share prices.
expected future abnormal earnings to certainty equivalents based on investors’ risk aversion across all possible events
and dates. (1) In this demonstration, Feltham and Ohlson (1999) measure abnormal earnings as earnings less a charge
for the cost of equity capital, basing the charge on the book value of equity and the term structure of risk-free interest
rates at the time of valuation. The pricing of risk therefore depends on the appropriate set of event-date-contingent prices
for future abnormal earnings measured as certainty equivalents. The Feltham and Orison (1999) demonstration is silent,
however, on how investors and empirical researchers should develop this complete set of event-date-contingent prices.
In the absence of implementable theoretical guidance, empirical applications of residual income valuation models have
incorporated risk into valuation by adding an ad hoc risk premium to a risk-free discount rate, with results that are
understandably sensitive to the risk premium assumption (e.g., Bernard 1994, 1995; Francis et al. 2000, 2001; Dechow et
al. 1999). Other recent studies invert the residual income valuation model to estimate the ex ante risk premia implicit in
discount rates, with mixed results (e.g., Claus and Thomas 2001; Gebhardt et al. 2001; Easton et al. 2000; Botosan and
Plumlee 2001, 2002). All of these prior studies use observed share values or stock returns to estimate the risk premia and
expected rates of return required by valuation models. Using observed share values or stock returns to assess risk
introduces a degree of circularity into valuation.
We develop a more direct approach that uses accounting numbers to assess firm risk and share values in a residual
income valuation context. First, we develop an accounting-based measure of the discount for risk inherent in share prices.
We estimate risk-free value based on the residual income model, analysts’ forecasts of earnings, and prevailing risk-free
rates of return. We then calculate the price differential--the risk-free value estimate minus share price. Conceptually, the
price differential is a simple yet theoretically defensible measure of the discount for risk implicit in share price. This
measure depends only on analysts’ expectations of earnings, the residual income valuation model, time value of money at
prevailing risk-free rates, and share price. The price differential is a potentially appealing firm-specific measure of the cost
of risk because it does not depend on any functional form of expected returns, or on explicit parameter estimates of
market risk measures (i.e., betas) or risk premia. As expected, price differentials are positive for nearly all firm-years
because risk-free values ignore the discounts for risk in share prices. As a practical matter, our estimates of price
differentials are highly positively correlated with estimates of expected rates of return implicit in share prices, but are
simpler to compute.
این مقاله کامل که در 59 صفحه ترجمه شده و به همراه متن اصلی عرضه می شود .
شناخت ریسک و بازده ، CAPM و مدل سه عاملی فاما – فرنچ
شناخت ریسک و بازده ، CAPM و مدل سه عاملی فاما – فرنچ
ریسک و بازده:
مفهوم عمومی: انتظار بازده بالاتر داشتن مستلزم پذیرش ریسک بیشتر است.
بسیاری از سرمایه گذاران به این نکته توجه دارند که پذیرش ریسک بالاتر برای دریافت بازده های بالاتر الزامی است. در این مقاله ما دو مدل مهم را برای توضیح این رابطه بکار گرفته وآنها را توضیح می دهیم. آنگاه توضیح خواهیم داد که چگونه این ابزارها می توانند بوسیله سرمایه گذاران برای ارزیابی داراییهایی همانند اوراق قرضه مورد استفاده قرار گیرند.
چرا باید شرکتهای با ریسک بالاتر درآمدهای بالاتری هم داشته باشند ؟ مسلمً یک سرمایه گذار به ازای پذیرش ریسک بالاتر ، نیاز به بازده پیش بینی شده بالاتری دارد. و ما در واقع این ارتباط را با بررسی بازده های بلند مدت تاریخی سهام، اوراق قرضه و داراییهای با ریسک کمتر ، همانگونه که در اولین نمودار آمده است ، مشاهده می کنیم.
برای درک این مطلب ، فرض کنید که یک سرمایه گذاری که پیش بینی شده است یک میلیون دلار را بطور مستمر و سالانه ایجاد کند ، انجام گرفته است. یک فرد برای یک چنین دارایی چقدر حاضر است بپردازد؟ پاسخ به نامشخص بودن یا ریسک پذیری گردش وجوه نقد بستگی دارد. با مشخص بودن کامل شرایط که در آن گردش وجوهخ نقد بهنگام قرارداد کاملاض مشخص می شود ، یک سرمایه گذار دارایی را با نرخ بدون ریسک در نظر خواهد گرفت . همچنانکه میزان نا مشخصی افزایش می یابد ،بازده مورد نیاز برای جبران ریسک افزایش می یابد و در نتیجه در قیمت پایینتری سرمایه گذار مایل به سرمایه گذاری است ، زیرا ریسک بالاتر مستلزم دادن تخفیف است.
بعلاوه اقتصاد دانان فرض می کنند که سرمایه گذاران ریسک گریز هستند ، به این معنا که آنها حاضرند از بخشی از بازده چشم پوشی کنند ( و حتی حاضرند کمتر از ارزش فعلی بازده آتی پیش بینی شده را دریافت کنند ) تا ریسک را کاهش دهند. اگر این فرض درست باشد،انتظار داریم سرمایه گذاران برای جبران ریسک اضافی پذیرفته شده بواسطه نگهداری داراییهای ریسک پذیرتر ، بازده بیشتری را تقاضا کنند.
بی ثباتی شاخصی برای ریسک:
یکی از معیارهای کاملاً پذیرفته شده برای ریسک ، بی ثباتی ، یعنی میزان تغییر بازده دارایی در دوره های زمانی موفق ، است که عموماً به صورت انحراف استاندارد بازده ها بیان می شود. یک دارایی که دارای نوسانات شدید است ، انتظار میرود که دارای ریسک بالاتری باشد ، زیرا ارزش دارایی در زمانی که سرمایه گذار می خواهد آنرا بفروشد کمتر از آنچه است که پیش بینی شده بود. بعلاوه ، بی ثباتی بالاتر از نظر آماری، به معنی این است که ارزش آتی و بالقوه یک دارایی که بی ثباتی بالایی دارد در رنج وسیعتری افت می کند.
Understanding Risk and Return, the CAPM,
and the Fama-French Three-Factor Model
RISK AND RETURN
The General Concept: Higher Expected Returns Require Taking Higher Risk
Most investors are comfortable with the notion that taking higher levels of risk is necessary to
expect to earn higher returns. In this note, we explain two important models that have been
developed to make this relationship precise. Then we explain how such tools can be used by
investors to evaluate assets such as mutual funds.
Why should riskier companies have higher returns? Intuitively, an investor would require a
higher expected return in exchange for accepting greater risk. And, we do, in fact observe this
relationship when we look back at historical long-run returns of stocks, bonds, and less risky
securities as shown in the first chart.
To understand this, imagine an investment that is expected to generate $1 million per year in
perpetuity. How much is someone likely to pay for such an asset? The answer depends on the
uncertainty or riskiness of the cash flows. With complete certainty that the cash flows will all be
paid when promised, an investor would discount the asset at the risk-free rate. As the degree of
uncertainty increases, the return required to justify the risk will be much higher, resulting in a
much lower price the investor would be willing to pay, simply because of the higher required
discount rate.
Furthermore, economists have made the assumption that investors are risk-averse, meaning that
they are willing to sacrifice some return (and accept even less than the expected present value of
the future returns) to reduce risk. If this assumption is true, we would expect investors to
demand a higher return to justify the additional risk accepted by holders of riskier assets.
Understanding Risk and Return, the CAPM, and the Fama-French Three-Factor Model
Tuck School of Business at Dartmouth, Case 03-111 2
Volatility as a Proxy for Risk
One widely accepted measure of risk is volatility, the amount that an asset’s return varies
through successive time periods, and is most commonly quoted in terms of the standard
deviation of returns. An asset whose return fluctuates dramatically is perceived to have greater
risk because the asset’s value at the time when the investor wishes to sell it is less predictable. In
addition, greater volatility means that, from a statistical perspective, the potential future values of
more volatile assets span a much wider range.
Diversification and Systematic Risk
Although somewhat counterintuitive, an individual stock’s volatility in and of itself, is not the
most important consideration when assessing risk. Consider a situation in which an investor
could, without incurring additional cost, reduce the volatility associated with her portfolio of
assets. This is most commonly accomplished through diversification. Consider holding two
stocks that have the same expected returns, instead of one stock. Because stock returns will not
be perfectly correlated with each other, it is unlikely that both stocks will experience extreme
movements (positive or negative) simultaneously, effectively reducing volatility of the overall
portfolio. As long as assets do not move in lock step with one another (are less than perfectly
Historical Annual Returns
(1926-1999)
18.81%
5.36%
3.82% 3.17%
13.11%
Small Stocks
39.68%
Large Stocks
20.21%
LT Gov’t Bonds
8.12%
US T-Bills
3.29%
Inflation
4.46%
Source: Stocks, Bonds, Bills and Inflation 2002 Yearbook, 2002 Ibbotson Associates
StDev (σ)
Understanding Risk and Return, the CAPM, and the Fama-French Three-Factor Model
Tuck School of Business at Dartmouth, Case 03-111 3
positively correlated), overall volatility can be reduced, without lowering expected returns, by
spreading the same amount of money across the multiple assets.
This concept of diversification is one of the main tenets of modern portfolio theory – volatility is
reduced through the addition of more assets to a portfolio. It should be noted, however, that the
rate of volatility reduction from adding assets decreases as the number of assets in the portfolio
increases. As the chart below demonstrates for one potential scenario (20% volatility on each
asset and zero covariance between assets), the general rule of thumb is that a portfolio containing
30 or more assets is considered well-diversified.
Diversifying Reduces Portfolio Volatility
0%
5%
10%
15%
20%
25%
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40
Number of Securities in Portfolio
Portfolio Standard Deviation .
Volatility can be effectively reduced without significant cost by diversifying, so it makes sense
that investors should not be compensated for that portion of volatility which is merely stock
specific and has no impact on a well diversified portfolio. This type of volatility is called
unsystematic risk in the finance literature because it does not covary with the market as a whole,
but is merely the additional random “noise” present in that specific asset’s returns. Since this
random noise has an expected return of zero, it can be diversified away by adding more
securities to the portfolio. Its mean will be zero, and its standard deviation will be reduced as
more assets are added.
جهت خرید این مقاله کامل که در 23 صفحه ترجمه شده و به همراه متن اصلی می باشد .
ریسک سود مازاد، ارزش‌های ذاتی و قیمت‌های سهام:
از استفن پی باجینسکی و جیمز ام والن ـ
تحقیقات تجربی حسابداری شواهد نسبتاً کمی در مورد این که آیا از نظر ریسک ، اختلافات مقطعی سودی حسابداری با اختلافات مقطعی در قیمت‌های سهام، ارتباط دارند یا نه؟ ارائه می‌دهد. ما با توجه به ریسک یا خطر مربوط به ارقام حسابداری دو پرسش را مطرح می‌کنیم:
1 ـ آیا ارزیابی‌های خطر مربوط به حسابداری (یعنی خطر نظام مند و تغییر پذیری کل در مجموعه زمانی بهره مازاد حقوق صاحبان سهام شرکت) با ارزیابی بازار و برآورد خطر حقوق صاحبان سهام ارتباطی دارد یا نه؟
2 ـ اگر این چنین است، پس آیا این ارزیابی‌ها به صورت افزایشی با ارزشیابی بازار و ارزیابی خطر حقوق صاحبان سهام در ورای دیگر عوامل قابل بررسی و مشاهده، نظیر عوامل موجود در الگوی سه عامل French, Fama (1992) ارتباط دارند؟ ما بر مبنای یک معیار اساسی حسابداری در مورد ریسک قیمت بازار اختلاف میان قیمت واقعی سهام و الگوی ارزشیابی سود مازاد بر پایه برآورد ارزش سهام و با استفاده از نرخ بهره بد ون ریسک را ارزیابی می‌کنیم.
نتایج ما حاکی از آن است که هم ریسک سیستماتیک و هم مجموع تغییر پذیری در بهره مازاد حقوق صاحبان سهام به طور ناقص تفاوت قیمت گذاری را نشان می‌دهد، و تأثیر توضیحی مجموع تغییر پذیری به عوامل فاما و فرنچ ـ بقای بازار، اندازه شرکت و نسبت ارزش بازار به ارزش دفتری ـ افزوده می‌شود.
Fundamental valuation of equity shares requires estimation of expected future payoffs and the risk inherent in those
payoffs. Existing research on the usefulness of accounting earnings numbers has devoted far more attention to their role
as payoff-relevant information than to their role as risk-relevant information. One exception is the seminal Beaver et al.
(1970) study, which shows that accounting-based risk measures are positively associated with market model beta, but
which does not examine whether accounting-based risk measures explain share prices or returns. Thus far, the empirical
accounting research literature has surprisingly little to say about whether accounting earnings numbers capture
cross-sectional differences in risk that are associated with cross-sectional differences in share prices. In this study, we
investigate the risk-relevance of accounting numbers by addressing the question: Are accounting earnings-based risk
measures associated with the capital market’s assessment and pricing of firm risk? The answer to this question will inform
capital markets participants, as well as accounting researchers and teachers, about the fundamental usefulness of
accounting earnings numbers in assessing and pricing risk. The findings will also contribute to a better understanding of
how to specify accounting earnings-based valuation models, and how to use them in settings in which market-based risk
measures (e.g., market model beta) are not available.
We also address a second question: Are accounting earnings-based risk measures incrementally associated with the
market’s assessment and pricing of equity risk beyond other observable risk factors, such as the three factors in the Fama
and French (1992) model (market model beta, firm size, and book-to-market ratios)? Research by Fama and French
(1992) and others shows that the single factor capital asset pricing model may be incomplete because ad hoc factors
outside of the model (including factors based on accounting numbers, such as the book-to-market ratio) appear to explain
stock returns. Our investigation contributes evidence on whether accounting earnings-based risk measures capture
elements of priced risk that traditional measures of equity risk (e.g., market model beta) or factors identified by more
recent ad hoc approaches to risk (e.g., Fama and French 1992) do not capture.
Traditional theory on the role of accounting numbers in valuation, such as the residual income valuation models (e.g.,
Ohlson 1995; Feltham and Ohlson 1995), simplify the role of risk by assuming that investors are risk neutral and discount
rates are nonstochastic and flat. More recently, Feltham and Ohlson (1999) point out that equity values should price as
fundamental risk the nondiversifiable variability inherent in expected future residual income. Feltham and Ohlson (1999)
demonstrate analytically that (at least in principle) one can incorporate risk in residual income valuation by reducing
Accounting Review Jan 2003 v78 i1 p327(25) Page 1
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Residual income risk, intrinsic values, and share prices.
expected future abnormal earnings to certainty equivalents based on investors’ risk aversion across all possible events
and dates. (1) In this demonstration, Feltham and Ohlson (1999) measure abnormal earnings as earnings less a charge
for the cost of equity capital, basing the charge on the book value of equity and the term structure of risk-free interest
rates at the time of valuation. The pricing of risk therefore depends on the appropriate set of event-date-contingent prices
for future abnormal earnings measured as certainty equivalents. The Feltham and Orison (1999) demonstration is silent,
however, on how investors and empirical researchers should develop this complete set of event-date-contingent prices.
In the absence of implementable theoretical guidance, empirical applications of residual income valuation models have
incorporated risk into valuation by adding an ad hoc risk premium to a risk-free discount rate, with results that are
understandably sensitive to the risk premium assumption (e.g., Bernard 1994, 1995; Francis et al. 2000, 2001; Dechow et
al. 1999). Other recent studies invert the residual income valuation model to estimate the ex ante risk premia implicit in
discount rates, with mixed results (e.g., Claus and Thomas 2001; Gebhardt et al. 2001; Easton et al. 2000; Botosan and
Plumlee 2001, 2002). All of these prior studies use observed share values or stock returns to estimate the risk premia and
expected rates of return required by valuation models. Using observed share values or stock returns to assess risk
introduces a degree of circularity into valuation.
We develop a more direct approach that uses accounting numbers to assess firm risk and share values in a residual
income valuation context. First, we develop an accounting-based measure of the discount for risk inherent in share prices.
We estimate risk-free value based on the residual income model, analysts’ forecasts of earnings, and prevailing risk-free
rates of return. We then calculate the price differential--the risk-free value estimate minus share price. Conceptually, the
price differential is a simple yet theoretically defensible measure of the discount for risk implicit in share price. This
measure depends only on analysts’ expectations of earnings, the residual income valuation model, time value of money at
prevailing risk-free rates, and share price. The price differential is a potentially appealing firm-specific measure of the cost
of risk because it does not depend on any functional form of expected returns, or on explicit parameter estimates of
market risk measures (i.e., betas) or risk premia. As expected, price differentials are positive for nearly all firm-years
because risk-free values ignore the discounts for risk in share prices. As a practical matter, our estimates of price
differentials are highly positively correlated with estimates of expected rates of return implicit in share prices, but are
simpler to compute.
این مقاله کامل که در 59 صفحه ترجمه شده و به همراه متن اصلی عرضه می شود .
هنر سرمایه گذاری با ریسک و بازده
ریسک وبازده:
هنر سرمایه گذاری با ریسک و بازده تعریف می شود. سرمایه گذاری به معنی قبول یک مقدار ریسک به ازای یک بازده مورد انتظار است.برای هر فرد قبل از ورود به بازار سهام این نکته کاملاً مهم است تا انواع مختلف ریسک و مخاطره را شناخته و آنها را اندازه گیری کند.همچنانکه که خواهیم دید برخی از این ریسک و بازده ها دارای تنوع هستند و برخی دیگر به این گونه نیستند.مطمئن شوید که شما آماده پرداخت برای رسیک اضافی هستید.
زمانیکه یک سرمایه گذار یک دارایی را خریداری میکند (سهام ، اوراق قرضه ، یک شرکت ، اثر هنری و غیره ) این داراییها دارای یک بازده مورد انتظار هستند.برخی از سرمایه گذاران این بازده را بر حسب درصد مشخص میکنند در حالیکه دیگران امیدوارند که این بازده به صورت مثبت باشد.بازده مورد انتظار از نظر ریاضی به صورت درآمد سرمایه پرداخت شده تعریف می شود.سهام خاص که عموماً در بخش تکنولوژی وجود دارند هیچ بازده (سود قابل تقسیم ) ندارند زیرا آنها تمامی سودها را در موسسه سرمایه گذاری می کنند. در مورد رشد این سهام بازده مورد انتظار شما همان سرمایه است. به خاطر داشته باشید که سرمایه گذاری همانند یک خیابان دو طرفه است که بین سرمایه گذار و شرکتی که شما می خواهید در آن سرمایه گذاری کنید قرار گرفته است. اگر شما سهام یک شرکت (یا اوراق قرضه آنها) را خریداری کنید ، آنها به شما بابت این کار یک پاداش مناسب را می دهند که می توانید آن را ردر جای دیگر سرمایه گذاری کنید. بنابراین بازده مورد انتظار بابت سرمایه گذاری یک سرمایه گذار باعث ایجاد یک سطح ریسک برای دارایی می شود.ریسک انواع مختلفی دارند که عبارتند از:
ریسک سیستماتیک:
این ریسکی است که نمی توانید آنرا متنوع کنید.زمانی که شما یک دارایی را خریداری می کنید عوامل متعددی در پی آن قرار می گیرند که می توانند بر بازده سرمایه گذاری (به صورت منفی یا مثبت )اثر بگذارند : نرخ ریسک سرمایه گذاری مجدد ، مخاطره بازار ، نرخ ریسک مبادله ، و ریسک قدرت خرید (تورم ) . هیچ راهی برای اینکه در دوره نوسان بتوانید از یک سهام خاص محافظت بکنید وجود ندارد. لطفاً به این نکته توجه داشته باشید که اگر چه شما نمی توانید در برابر این مخاطرات حفاظتی داشته باشید ولی راههایی وجود دارند که از انها دوری نمایید. یک را می تواند خرید یک بیمه با نرخ شناور است که از سهام هنگام افزایش منفی در نرخ بهره بازار حمایت میکند.
Risk and Return
The art of "investing" is defined by risk and return. An investor is willing to assume a certain amount of risk as a trade-off to getting paid an expected return. It is quite important for any person, prior to jumping into the stock market, to understand the different types of risk and how to measure them. As we will see, some types can be circumvented through diversification, while others cannot. Be sure you are getting paid for the added risk you take!
When an investor buys a security (stock, bond, mutual fund, artwork, etc) they have a certain "expected return." Some investors may quantify this number as a percentage, while others just hope for some sort of positive return. Expected return is mathematically defined as income capital appreciation. Certain stocks, generally in the technology sector, do not pay any income (dividends) because they reinvest all profits in their business. In the case of these (growth) stocks, your expected return is strictly capital appreciation. Keep in mind that investing is a two-way street between the investor and the company you are investing in. If you buy a stock position in a company (or a bond from them) they have to give you an adequate reward for doing so or you"ll invest elsewhere. Thus, the "required return" is what will induce an investor to invest in an asset, given that asset`s level of risk. There are a few types of risk:
systematic risk- this is risk which cannot be diversified. When you buy a security it is subject to the following unpredictable factors which may affect (either positively or negatively) your return on investment: interest rate risk, reinvestment rate risk, market risk, exchange rate risk, and purchasing power (inflation) risk. There is nothing you can do to protect an individual stock from an inflationary period. Please note that even though you cannot prevent these risks, there are still ways to hedge them. An example would be buying a floating rate mortgage security to protect a stock which may tend to perform negatively in a rising interest-rate environment.
unsystematic risk- this component of risk can be diversified by having a "portfolio" of securities. Diversifiable risks include business risk, financial risk, and country risk. For example, if you have $10,000 and buy a homebuilding stock with it, you are not diversifying your risks. If the overall stock market goes up, but the housing sector slows down, your stock will underperform the overall market. Many investment professionals believe that owning a basket of roughly 10-15 stocks in different sectors can eliminate most of the unsystematic risk.
The most important measure of a security`s risk is its standard deviation. This is a statistical measure of the historical volatility of a portfolio of securities, usually figured with a 5, or 10-year return. In simpler terms, standard deviation is a measure of how much investment returns tend to fluctuate around their average. To compute standard deviation, you need to write down the % return each year for a specific stock or mutual fund. You then add them all up and divide by the number of securities you are using. This will give you the "mean" or average return of the portfolio over a period of time. You subtract the mean from each annual return and then square it. You add up all these squared numbers, divide by the number of years, and take the square root. This will give you the "standard deviation." A portfolio will move within 1 standard deviation (whatever the number is) 68% of the time. It will move within 2 standard deviations 98% of the time. This is an important way to assess potential risk and return from a portfolio of securities. Check out this profile page from yahoo.com which goes into the statistical measure of “risk.”
Risk
Risk means the probability that you will lose money on an investment. A more technical definition of risk is the volatility of return on the investment. An asset with erratic returns is considered riskier than an asset whose value is static or moves slowly.
Few investments are risk-free. Investing in stocks, in particular, means accepting some level of risk. If you want to make a killing in the stock market, you are going to have to take risks. If you keep all your life savings in safe investments such as a savings account, you will face virtually no risk, but your returns will be small, and inflation will eat away at the value of your deposit.
There is a trade-off between risk and return. Less risk means less return, while taking on more risk brings the possibility of a higher return.
Levels of risk are a personal decision. They may be affected by your age, investment goals, time of life and how much you can afford to lose.
Types of risk
There are two types of risks to consider when investing in the stock market - the market risk and unique risks.
جهت خرید این مقاله کامل که در 22 صفحه ترجمه شده و به همراه متن اصلی می باشد . شما هم اکنون می توانید با اتصال به یکی از درگاههای پرداخت آنلاین بانک های ملت و یا اقتصاد نوین نسبت به پرداخت آنلاین هزینه اقدام نمایید و بلافاصله پس از پرداخت فایل را به صورت کامل از سایت و یا ایمیل دریافت کنید.
شناخت ریسک و بازده ، CAPM و مدل سه عاملی فاما – فرنچ
شناخت ریسک و بازده ، CAPM و مدل سه عاملی فاما – فرنچ
ریسک و بازده:
مفهوم عمومی: انتظار بازده بالاتر داشتن مستلزم پذیرش ریسک بیشتر است.
بسیاری از سرمایه گذاران به این نکته توجه دارند که پذیرش ریسک بالاتر برای دریافت بازده های بالاتر الزامی است. در این مقاله ما دو مدل مهم را برای توضیح این رابطه بکار گرفته وآنها را توضیح می دهیم. آنگاه توضیح خواهیم داد که چگونه این ابزارها می توانند بوسیله سرمایه گذاران برای ارزیابی داراییهایی همانند اوراق قرضه مورد استفاده قرار گیرند.
چرا باید شرکتهای با ریسک بالاتر درآمدهای بالاتری هم داشته باشند ؟ مسلمً یک سرمایه گذار به ازای پذیرش ریسک بالاتر ، نیاز به بازده پیش بینی شده بالاتری دارد. و ما در واقع این ارتباط را با بررسی بازده های بلند مدت تاریخی سهام، اوراق قرضه و داراییهای با ریسک کمتر ، همانگونه که در اولین نمودار آمده است ، مشاهده می کنیم.
برای درک این مطلب ، فرض کنید که یک سرمایه گذاری که پیش بینی شده است یک میلیون دلار را بطور مستمر و سالانه ایجاد کند ، انجام گرفته است. یک فرد برای یک چنین دارایی چقدر حاضر است بپردازد؟ پاسخ به نامشخص بودن یا ریسک پذیری گردش وجوه نقد بستگی دارد. با مشخص بودن کامل شرایط که در آن گردش وجوهخ نقد بهنگام قرارداد کاملاض مشخص می شود ، یک سرمایه گذار دارایی را با نرخ بدون ریسک در نظر خواهد گرفت . همچنانکه میزان نا مشخصی افزایش می یابد ،بازده مورد نیاز برای جبران ریسک افزایش می یابد و در نتیجه در قیمت پایینتری سرمایه گذار مایل به سرمایه گذاری است ، زیرا ریسک بالاتر مستلزم دادن تخفیف است.
بعلاوه اقتصاد دانان فرض می کنند که سرمایه گذاران ریسک گریز هستند ، به این معنا که آنها حاضرند از بخشی از بازده چشم پوشی کنند ( و حتی حاضرند کمتر از ارزش فعلی بازده آتی پیش بینی شده را دریافت کنند ) تا ریسک را کاهش دهند. اگر این فرض درست باشد،انتظار داریم سرمایه گذاران برای جبران ریسک اضافی پذیرفته شده بواسطه نگهداری داراییهای ریسک پذیرتر ، بازده بیشتری را تقاضا کنند.
بی ثباتی شاخصی برای ریسک:
یکی از معیارهای کاملاً پذیرفته شده برای ریسک ، بی ثباتی ، یعنی میزان تغییر بازده دارایی در دوره های زمانی موفق ، است که عموماً به صورت انحراف استاندارد بازده ها بیان می شود. یک دارایی که دارای نوسانات شدید است ، انتظار میرود که دارای ریسک بالاتری باشد ، زیرا ارزش دارایی در زمانی که سرمایه گذار می خواهد آنرا بفروشد کمتر از آنچه است که پیش بینی شده بود. بعلاوه ، بی ثباتی بالاتر از نظر آماری، به معنی این است که ارزش آتی و بالقوه یک دارایی که بی ثباتی بالایی دارد در رنج وسیعتری افت می کند.
Understanding Risk and Return, the CAPM,
and the Fama-French Three-Factor Model
RISK AND RETURN
The General Concept: Higher Expected Returns Require Taking Higher Risk
Most investors are comfortable with the notion that taking higher levels of risk is necessary to
expect to earn higher returns. In this note, we explain two important models that have been
developed to make this relationship precise. Then we explain how such tools can be used by
investors to evaluate assets such as mutual funds.
Why should riskier companies have higher returns? Intuitively, an investor would require a
higher expected return in exchange for accepting greater risk. And, we do, in fact observe this
relationship when we look back at historical long-run returns of stocks, bonds, and less risky
securities as shown in the first chart.
To understand this, imagine an investment that is expected to generate $1 million per year in
perpetuity. How much is someone likely to pay for such an asset? The answer depends on the
uncertainty or riskiness of the cash flows. With complete certainty that the cash flows will all be
paid when promised, an investor would discount the asset at the risk-free rate. As the degree of
uncertainty increases, the return required to justify the risk will be much higher, resulting in a
much lower price the investor would be willing to pay, simply because of the higher required
discount rate.
Furthermore, economists have made the assumption that investors are risk-averse, meaning that
they are willing to sacrifice some return (and accept even less than the expected present value of
the future returns) to reduce risk. If this assumption is true, we would expect investors to
demand a higher return to justify the additional risk accepted by holders of riskier assets.
Understanding Risk and Return, the CAPM, and the Fama-French Three-Factor Model
Tuck School of Business at Dartmouth, Case 03-111 2
Volatility as a Proxy for Risk
One widely accepted measure of risk is volatility, the amount that an asset’s return varies
through successive time periods, and is most commonly quoted in terms of the standard
deviation of returns. An asset whose return fluctuates dramatically is perceived to have greater
risk because the asset’s value at the time when the investor wishes to sell it is less predictable. In
addition, greater volatility means that, from a statistical perspective, the potential future values of
more volatile assets span a much wider range.
Diversification and Systematic Risk
Although somewhat counterintuitive, an individual stock’s volatility in and of itself, is not the
most important consideration when assessing risk. Consider a situation in which an investor
could, without incurring additional cost, reduce the volatility associated with her portfolio of
assets. This is most commonly accomplished through diversification. Consider holding two
stocks that have the same expected returns, instead of one stock. Because stock returns will not
be perfectly correlated with each other, it is unlikely that both stocks will experience extreme
movements (positive or negative) simultaneously, effectively reducing volatility of the overall
portfolio. As long as assets do not move in lock step with one another (are less than perfectly
Historical Annual Returns
(1926-1999)
18.81%
5.36%
3.82% 3.17%
13.11%
Small Stocks
39.68%
Large Stocks
20.21%
LT Gov’t Bonds
8.12%
US T-Bills
3.29%
Inflation
4.46%
Source: Stocks, Bonds, Bills and Inflation 2002 Yearbook, 2002 Ibbotson Associates
StDev (σ)
Understanding Risk and Return, the CAPM, and the Fama-French Three-Factor Model
Tuck School of Business at Dartmouth, Case 03-111 3
positively correlated), overall volatility can be reduced, without lowering expected returns, by
spreading the same amount of money across the multiple assets.
This concept of diversification is one of the main tenets of modern portfolio theory – volatility is
reduced through the addition of more assets to a portfolio. It should be noted, however, that the
rate of volatility reduction from adding assets decreases as the number of assets in the portfolio
increases. As the chart below demonstrates for one potential scenario (20% volatility on each
asset and zero covariance between assets), the general rule of thumb is that a portfolio containing
30 or more assets is considered well-diversified.
Diversifying Reduces Portfolio Volatility
0%
5%
10%
15%
20%
25%
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40
Number of Securities in Portfolio
Portfolio Standard Deviation .
Volatility can be effectively reduced without significant cost by diversifying, so it makes sense
that investors should not be compensated for that portion of volatility which is merely stock
specific and has no impact on a well diversified portfolio. This type of volatility is called
unsystematic risk in the finance literature because it does not covary with the market as a whole,
but is merely the additional random “noise” present in that specific asset’s returns. Since this
random noise has an expected return of zero, it can be diversified away by adding more
securities to the portfolio. Its mean will be zero, and its standard deviation will be reduced as
more assets are added.
جهت خرید این مقاله کامل که در 23 صفحه ترجمه شده و به همراه متن اصلی می باشد .
شناخت ریسک و بازده ، CAPM و مدل سه عاملی فاما – فرنچ
شناخت ریسک و بازده ، CAPM و مدل سه عاملی فاما – فرنچ
ریسک و بازده:
مفهوم عمومی: انتظار بازده بالاتر داشتن مستلزم پذیرش ریسک بیشتر است.
بسیاری از سرمایه گذاران به این نکته توجه دارند که پذیرش ریسک بالاتر برای دریافت بازده های بالاتر الزامی است. در این مقاله ما دو مدل مهم را برای توضیح این رابطه بکار گرفته وآنها را توضیح می دهیم. آنگاه توضیح خواهیم داد که چگونه این ابزارها می توانند بوسیله سرمایه گذاران برای ارزیابی داراییهایی همانند اوراق قرضه مورد استفاده قرار گیرند.
چرا باید شرکتهای با ریسک بالاتر درآمدهای بالاتری هم داشته باشند ؟ مسلمً یک سرمایه گذار به ازای پذیرش ریسک بالاتر ، نیاز به بازده پیش بینی شده بالاتری دارد. و ما در واقع این ارتباط را با بررسی بازده های بلند مدت تاریخی سهام، اوراق قرضه و داراییهای با ریسک کمتر ، همانگونه که در اولین نمودار آمده است ، مشاهده می کنیم.
برای درک این مطلب ، فرض کنید که یک سرمایه گذاری که پیش بینی شده است یک میلیون دلار را بطور مستمر و سالانه ایجاد کند ، انجام گرفته است. یک فرد برای یک چنین دارایی چقدر حاضر است بپردازد؟ پاسخ به نامشخص بودن یا ریسک پذیری گردش وجوه نقد بستگی دارد. با مشخص بودن کامل شرایط که در آن گردش وجوهخ نقد بهنگام قرارداد کاملاض مشخص می شود ، یک سرمایه گذار دارایی را با نرخ بدون ریسک در نظر خواهد گرفت . همچنانکه میزان نا مشخصی افزایش می یابد ،بازده مورد نیاز برای جبران ریسک افزایش می یابد و در نتیجه در قیمت پایینتری سرمایه گذار مایل به سرمایه گذاری است ، زیرا ریسک بالاتر مستلزم دادن تخفیف است.
بعلاوه اقتصاد دانان فرض می کنند که سرمایه گذاران ریسک گریز هستند ، به این معنا که آنها حاضرند از بخشی از بازده چشم پوشی کنند ( و حتی حاضرند کمتر از ارزش فعلی بازده آتی پیش بینی شده را دریافت کنند ) تا ریسک را کاهش دهند. اگر این فرض درست باشد،انتظار داریم سرمایه گذاران برای جبران ریسک اضافی پذیرفته شده بواسطه نگهداری داراییهای ریسک پذیرتر ، بازده بیشتری را تقاضا کنند.
بی ثباتی شاخصی برای ریسک:
یکی از معیارهای کاملاً پذیرفته شده برای ریسک ، بی ثباتی ، یعنی میزان تغییر بازده دارایی در دوره های زمانی موفق ، است که عموماً به صورت انحراف استاندارد بازده ها بیان می شود. یک دارایی که دارای نوسانات شدید است ، انتظار میرود که دارای ریسک بالاتری باشد ، زیرا ارزش دارایی در زمانی که سرمایه گذار می خواهد آنرا بفروشد کمتر از آنچه است که پیش بینی شده بود. بعلاوه ، بی ثباتی بالاتر از نظر آماری، به معنی این است که ارزش آتی و بالقوه یک دارایی که بی ثباتی بالایی دارد در رنج وسیعتری افت می کند.
Understanding Risk and Return, the CAPM,
and the Fama-French Three-Factor Model
RISK AND RETURN
The General Concept: Higher Expected Returns Require Taking Higher Risk
Most investors are comfortable with the notion that taking higher levels of risk is necessary to
expect to earn higher returns. In this note, we explain two important models that have been
developed to make this relationship precise. Then we explain how such tools can be used by
investors to evaluate assets such as mutual funds.
Why should riskier companies have higher returns? Intuitively, an investor would require a
higher expected return in exchange for accepting greater risk. And, we do, in fact observe this
relationship when we look back at historical long-run returns of stocks, bonds, and less risky
securities as shown in the first chart.
To understand this, imagine an investment that is expected to generate $1 million per year in
perpetuity. How much is someone likely to pay for such an asset? The answer depends on the
uncertainty or riskiness of the cash flows. With complete certainty that the cash flows will all be
paid when promised, an investor would discount the asset at the risk-free rate. As the degree of
uncertainty increases, the return required to justify the risk will be much higher, resulting in a
much lower price the investor would be willing to pay, simply because of the higher required
discount rate.
Furthermore, economists have made the assumption that investors are risk-averse, meaning that
they are willing to sacrifice some return (and accept even less than the expected present value of
the future returns) to reduce risk. If this assumption is true, we would expect investors to
demand a higher return to justify the additional risk accepted by holders of riskier assets.
Understanding Risk and Return, the CAPM, and the Fama-French Three-Factor Model
Tuck School of Business at Dartmouth, Case 03-111 2
Volatility as a Proxy for Risk
One widely accepted measure of risk is volatility, the amount that an asset’s return varies
through successive time periods, and is most commonly quoted in terms of the standard
deviation of returns. An asset whose return fluctuates dramatically is perceived to have greater
risk because the asset’s value at the time when the investor wishes to sell it is less predictable. In
addition, greater volatility means that, from a statistical perspective, the potential future values of
more volatile assets span a much wider range.
Diversification and Systematic Risk
Although somewhat counterintuitive, an individual stock’s volatility in and of itself, is not the
most important consideration when assessing risk. Consider a situation in which an investor
could, without incurring additional cost, reduce the volatility associated with her portfolio of
assets. This is most commonly accomplished through diversification. Consider holding two
stocks that have the same expected returns, instead of one stock. Because stock returns will not
be perfectly correlated with each other, it is unlikely that both stocks will experience extreme
movements (positive or negative) simultaneously, effectively reducing volatility of the overall
portfolio. As long as assets do not move in lock step with one another (are less than perfectly
Historical Annual Returns
(1926-1999)
18.81%
5.36%
3.82% 3.17%
13.11%
Small Stocks
39.68%
Large Stocks
20.21%
LT Gov’t Bonds
8.12%
US T-Bills
3.29%
Inflation
4.46%
Source: Stocks, Bonds, Bills and Inflation 2002 Yearbook, 2002 Ibbotson Associates
StDev (σ)
Understanding Risk and Return, the CAPM, and the Fama-French Three-Factor Model
Tuck School of Business at Dartmouth, Case 03-111 3
positively correlated), overall volatility can be reduced, without lowering expected returns, by
spreading the same amount of money across the multiple assets.
This concept of diversification is one of the main tenets of modern portfolio theory – volatility is
reduced through the addition of more assets to a portfolio. It should be noted, however, that the
rate of volatility reduction from adding assets decreases as the number of assets in the portfolio
increases. As the chart below demonstrates for one potential scenario (20% volatility on each
asset and zero covariance between assets), the general rule of thumb is that a portfolio containing
30 or more assets is considered well-diversified.
Diversifying Reduces Portfolio Volatility
0%
5%
10%
15%
20%
25%
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40
Number of Securities in Portfolio
Portfolio Standard Deviation .
Volatility can be effectively reduced without significant cost by diversifying, so it makes sense
that investors should not be compensated for that portion of volatility which is merely stock
specific and has no impact on a well diversified portfolio. This type of volatility is called
unsystematic risk in the finance literature because it does not covary with the market as a whole,
but is merely the additional random “noise” present in that specific asset’s returns. Since this
random noise has an expected return of zero, it can be diversified away by adding more
securities to the portfolio. Its mean will be zero, and its standard deviation will be reduced as
more assets are added.
جهت خرید این مقاله کامل که در 23 صفحه ترجمه شده و به همراه متن اصلی می باشد .
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