Stock market behavior: a fractal analysis of Saudi Stock Exchange.
Abdulhadi, Dhari Al ; Shetty, Shekar ; Alshamali, Mansour 等
I. INTRODUCTION
This study attempts to investigate the efficiency of the Saudi
stock market using fractal analysis. In this study, we estimate the
fractal dimension of price returns and test the Efficient Market
Hypothesis (EMH), employing rescaled range analysis in order to use
fewer assumptions about the underlying system. This test is used instead
of other tests of EMH, like the autocorrelation test, runs test, and
simple volatility test, because it does not assume a normal distribution
as well as allowing for different distributions such as fat tails, and
power laws present in the time series, which may appear more pragmatic.
Applying standard asset pricing models is not appropriate due to
the random walk assumption. This is evident because of the presence of
stock market inefficiency and bias of security returns. The validity of
the random walk assumption determines the accuracy of the asset pricing
models. The Saudi stock market is typified by thinly traded stocks and
high index weights for some companies. Of the few studies performed on
stock market efficiency in Saudi Arabia, most are done to test the
conventional weak-form of the EMH.
The paper is organized as follows: Section II presents review of
related literature; Section III describes methodology and sources of
data; Section IV provides results; and the final section gives
conclusions of the study.
II. ANALYTICAL APPROACH AND HISTORICAL PERSPECTIVE
The French mathematician, Louis Bachelier (1900), first studied
market efficiency in his "Theory of Speculation," and his
method was independently re-discovered by Albert Einstein five years
later, and that made Paul Samuelson to call it Bachelier-Einstein
approach to Brownian dynamics. Bachelier characterized stock market
speculation as "fair game" (or Martingale property) of an
unbiased random walk wherein no speculator could earn excess returns due
to random price fluctuations. His study was popularized in late 1950 and
was translated to English in 1964 by Paul Cootner. Cootner in his works
(1960, 1960) amplified his take on the issue.
Let us sketch the Bachelier-Einstein derivation of the partial
differential equation of probability diffusion of Fokker-Plank variety
by going through partial difference equations. Considering n = log x,
Bachelier's expression was as follows:
[P.sub.n.t] = 1/2 [P.sub.n+1,t-1] + 1/2 [P.sub.n-1,t-1]
or
[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]
If [DELTA]t [right arrow] 0, with [DELTA]/t/[([DELTA]n).sup.2]
[right arrow] 2[c.sup.2].
Paul Samuelson (1965a) gets the Fourier parabolic equation from the
above as follows:
[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]
Samuelson (1965a, 1965b, 1969 with Robert Merton) - in three
successive papers contributed further to the early ideas of market
efficiency. Most importantly, he took the absolute Brownian motion that
admits of negative price with high probabilities into geometric Brownian
dynamics for meaningful economic model whereby Bachelier's
structure:
P(X,x;T) [equivalent to] P(X - x;T)
is changed into
P(X,x;T) [equivalent to] P(X/x; T), x > 0
P(X,0;T) [equivalent to] 1
for all X > 0.
Many scholars, e.g., Sprenkle (1961), Osborne (1959), Boness
(Cootner, 1964), and so on, have magnified and made meaningful advances
even before Samuelson's works in print. In his doctoral
dissertation, Fama (1965) proposed the tenets of the EMH as well as the
definition for efficient markets: "A market where there are large
numbers of rational, profit-maximizers, actively competing, with each
trying to predict future market values of individual securities, and
where important current information is almost freely available to all
participants. In an efficient market, competition among the many
intelligent participants leads to a situation where, at any point in
time, actual prices of individual securities already reflect the effects
of information based both on events that have already occurred and on
events which, as of now, the market expects to take place in the future.
In other words, in an efficient market at any point in time the actual
price of a security will be a good estimate of its intrinsic
value."
A more restrictive random walk model requires independence
involving higher conditional moments like the variance, skewness, and
kurtosis of the probability distribution of price changes. Unlike the
random walk model in which they are largely alike, the efficient market
hypothesis requires only the independence of the conditional expectation
of price changes from the available information.
Three forms of market efficiency were outlined by Roberts (1967).
Weak form efficient markets cannot consistently earn excess returns
using past prices and returns. Semi-strong efficient markets cannot
consistently earn excess returns using public information. Finally, a
market which is 'strongly efficient' cannot consistently earn
excess returns using private information or, for that matter, any
information.
The joint hypothesis problem (Fama, 1965) has shown that, barring a
rejection of the model of market equilibrium, or the price setting
mechanism in which it states that when a model yields a return
significantly differ from the actual return, market efficiency could not
be rejected. One could never confirm the existence of an imperfection in
the model or conclude the market is inefficient. The model can only be
changed through the addition of factors to account for the return, or
alpha. The alpha is not a result of a flaw in the model or of market
inefficiency.
A measure of the independence of changes in prices or returns,
which is the conventional approach using only historical asset prices,
is necessary in order to statistically test the efficient market
hypothesis. Finding the presence of significant independence is evidence
of weak sense market efficiency which is widely tested. Kendall (1953)
examined 22 stock and commodity prices in the UK and found them to be
efficient. Using daily price data from 1957 to 1962, Fama (1965) tested
30 Dow Jones Industrial Average stocks utilizing serial correlation and
concluded that the Dow was efficient. Emerging markets also exhibited
weak-form efficiency. In Singapore (Hong, 1978), Malaysia (Barnes,
1986), and Greece (Panas, 1990). Granger and Morgenstern (1963) used the
spectral analysis technique to examine the New York Stock Exchange
finding no significant serial correlation.
Although early empirical studies tended to favor the EMH, more
current studies indicate a tendency for a lack of resilience of the EMH
in stock returns, even in its weak-form. This may be an indication of
some degree of asset price predictability. Lo and MacKinlay (1988)
proposed using a variance ratio test which is based on comparing
variance estimators derived from data sampled at different frequencies.
Interestingly, when they used this test for weekly returns in the US
stock market from 1962 to 1985, they strongly rejected the random walk
hypothesis. When Poterba and Summers (1988) examined mean reversion in
US stock prices using the variance ratio test on monthly data they found
positive serial correlation in stock returns for periods of less than
one year, and negative serial correlation in longer horizon returns.
Fama and French (1988) found similar autocorrelation patterns.
In emerging markets Wong and Kwong (1984) used the runs test to
examine the weak form efficiency in the Hong Kong stock market and
concluded that it is inefficient. Urrutia (1995), argued for the
rejection of the random walk hypothesis when using the variance ratio
test to study market efficiency in four major Latin American stock
markets (Argentina, Brazil, Chile, and Mexico).
Of the few studies involving Saudi Arabian stock market efficiency,
most investigated the conventional weak-form of the EMH. Emerging
markets are more likely to be inefficient due to their small size, thin
trading, and lack of regulation. The empirical findings of Saudi and
Kuwaiti stock market efficiency also indicate a tendency toward market
inefficiency, although there are a few weak-form efficient markets.
Gandhi et al. (1980), studied efficiency in the Kuwaiti Stock Exchange
(KSE) for the period of 1975 to 1978. They tested KSE for market
efficiency, using autocorrelation coefficients test, runs test, and
simple volatility tests, and they found that stock prices are highly
serially correlated and volatile, thus concluding that KSE is
inefficient. Butler and Malaikah (1992) examined efficiency of Saudi and
Kuwaiti stock markets from 1985 to 1989 on individual stock returns,
using serial correlation and runs tests with similar results. These
results indicated significant serial correlation in both markets, which
can be considered clear evidence of market inefficiency. Other studies
have also found market inefficiency in the stock markets of Saudi Arabia
(Nourredine, 1998) and Kuwait (Al-Loughani, 1995). Moreover, a more
recent research of Elango and Hussein (2008) has shown by virtue of runs
test that the stock markets of Kuwait, Saudi Arabia, UAE, Oman, Qatar,
and Bahrain (GCC Countries) the weak-form efficiency could be rejected
for all GCC markets from 2001 to 2006.
A few other studies, however, did indicate weak-form efficiency in
some gulf stock markets. One such study was by Dahel and Labbas (1999),
who examined the random behavior of stock markets of Saudi Arabia,
Kuwait, Bahrain, and Oman. They were unable to reject the random walk
hypothesis when they used unit root, autocorrelation, and variance ratio
tests. That suggests that these markets were distinguished by weak-form
efficiency. Abraham et al. (2002) used the runs test and variance ratio
test to examine efficiency in the GCC stock markets of Saudi Arabia,
Kuwait, and Bahrain. They found indications of weak-form market
efficiency in Saudi Arabia and Bahrain, but not in Kuwait. Inconsistent
outcomes have occurred in many cases of developed and emerging markets.
III. METHODOLOGY AND DATA
Since random walk (martingale) is not applicable in this case, we
employ the Hurst Exponent (Hurst, 1951) to test the EMH because it
affords a measure for both long-term memory and fractality of a time
series, has fewer assumptions about the underlying system, and does not
assume a normal distribution. Hurst's allowance of different
distributions, fat tails, and power laws present in the time series is
advantageous in that it more closely resembles reality and permits a
measure of the long-memory in the time series. Hurst exponent (H)
measures the impact of information on the series. A value of H = .50
implies a random walk, confirming the EMH, i.e., yesterday's events
do not impact today's and today's events do not impact
tomorrow's. This means the events are not correlated which
indicates that old news has already been absorbed and discounted by the
market. An H exceeding 0.50, however, suggests today's events do
impact tomorrow's. Thus, information received today continues to be
discounted by the market after it has been received. This is not a
simple serial correlation, where the impact of information simply
decays, but a longer memory function where information can impact the
future for longer timespan. It is important to bear in mind, while
utilizing this view of time-series analysis, that fractal distributions
are additive; that is, increments of time have individual transactions
embedded in them. Additional observations are not needed, but longer
time series are.
A Fractal dimension is a number that quantifies how an object fills
its space. In Euclidean geometry, objects are solid and have integer
dimensions. Fractals are rough and discontinuous like coastlines and do
not have an integer as a dimension. The Hurst is directly related to the
fractal dimension of a time series, which is the measure of the
roughness of the process. The fractal dimension is equal to D = 2 - H,
where H represents the Hurst exponent. The Hurst is an estimate, not a
definitive measure. We used a rescaled range (R/S) analysis in this
study to estimate it. To determine if the value of the Hurst was robust,
a Monte Carlo simulations of random numbers was done. Then the Hurst was
computed for the random series. To further check robustness, the data
series was tested using a scrambled Hurst. The time series was scrambled
after which the Hurst was calculated. If there was an underlying
structure in the data series it should have been destroyed with the
scrambled Hurst and a value close to the Hurst of a random series should
have emerged.
The values of the Hurst Exponent range between 0 and 1 and the
values of the fractal dimension range from 1 to 2. A Fractal Dimension
of 1.5, or a Hurst of 0.5 indicates a random walk, where there is no
long memory process among the data. This type of series is hard to
predict.
A Fractal Dimension of greater than 1.5, or a Hurst exponent
between 0 and 0.5 indicates an anti-persistent behavior in which an
increasing trend will be followed by a decreasing one, which is referred
to as mean reverting. A Fractal dimension of less than 1.5 or a Hurst
exponent between 0.5 and 1 indicates persistent and trending behavior.
The Hurst is different from volatility, in which a stock can have a
relatively low volatility while having an H close to 0.5. Matured
markets usually have a Fractal Dimension closer to 1.5 and a Hurst
closer to 0.5 than emerging markets.
Thiele (2007) tested China's stock market prior to and
subsequent to reforms applying fractal dimension. The rescaled (R/S)
analysis showed that the markets had a biased random walk reporting a
fractal dimension of less than 1.5. This will be one of our base
methodologies to test efficiency.
Qian and Rasheed (2004) used the Hurst exponent to establish the
predictability of the time-series as well as to estimate the embedding
dimension and separation. These are concepts from chaos theory which use
auto mutual information and false nearest neighbor methods. They then
utilized neural networks to predict the returns on the Dow-Jones index
in which they found periods with large Hurst exponents could be
predicted more accurately than those with values close to a random
series. The results indicated that stock markets can have periods of
strong trend structure and others that are random. The periods of strong
trend structure can be learned by the neural network. The authors found
more accurate results from the use of the Hurst exponent before trying
to build a model, and that it saved effort and time. This model will be
utilized in this study.
In another investigation, Qian and Rasheed (2007), used multiple
classifiers including artificial neural networks, k-nearest neighbor and
the decision tree method to predict stock market prices. Utilizing an
ensemble approach to improve prediction performance, they grouped the
different forecasting methods in various ways to produce a 60% accurate
prediction rate. The researchers expected ensembles of multiple
classifiers to become popular in the field of financial prediction in
the near future.
Studies of GCC stock markets are scarce. One barrier is the fact
that these markets are populated by thinly traded stocks and high index
weights for some companies. To deal with this issue, data for ordinary
shares in the Saudi Stock Exchange will be examined during a period of
five years for the largest three constituents of MSCI (Morgan Stanley
Capital International) Domestic index. The index is adjusted for free
float as well as for minimum float, liquidity and size guidelines. Free
float adjusted means the government holds shares which are not traded
and are accounted for in the index by taking them out of the weight. We
will use the largest weighted three stocks in the index since they will
represent the majority of the index.
Reuter's historical database was utilized as the source of
data because it was the first company in the region to be supplied with
historical financial information. To lessen the likelihood of
data-snooping bias, data were adapted for dividends and splits. We used
the raw data of financial time series of the Close and limited the
examination period to five years, the accepted interval of the three
stocks for comparison. The frequency of the data was set to daily data.
Saudi Arabia is the biggest economy in the region with a stock
market capitalization of over half a trillion dollars. Tadawul is the
only stock exchange in the country and it lists 167 publicly traded
companies. The Tadawul All Share Index consists of all the listed
companies in Saudi Arabia.
The MSCI indices are the benchmark of established investors in the
region because they use them to measure their tracking error and deem
them an ideal substitution for the Saudi Arabian market. To attend to
the issue of survivorship bias (the propensity for failed companies to
be omitted from performance studies) the three most highly weighted
companies rather than the index were chosen.
The MSCI Saudi Arabia Domestic Index was created in 2006 and it
measures the performance of the large and mid-cap stocks of the Saudi
Arabia market. This index covers approximately 85% of the free
float-adjusted market capitalization in Saudi Arabia. The three
constituents of the MSCI Saudi Arabia Domestic Index are Saudi Basic
Industries Corp. (2010.SA), AlRajhi Bank (2230.SA), and Etihad Etisalat
Co. (7020.SA). These companies account for 21.87%, 15.96%, and 6.17% of
the weighting of the MSCI Saudi Arabian Domestic Index at the time of
the research (Sept 2010). All the stocks are of high liquidity in their
markets in which they were traded on more than 90% of the trading days
in the market. Below is a brief overview of these three companies.
IV. RESULTS
A. Saudi Basic Industries Corp. (2010.SA)
Saudi Arabian Basic Industries Corporation (SABIC) is one of the
world's leading petrochemical companies. It is the largest public
company in the region. The Saudi Government owns 70% of its shares.
SABIC is the third largest polyethylene manufacturer, the fourth largest
polyolefins manufacturer and the fourth largest polypropylene
manufacturer. SABIC is also the world's largest producer of
monoethylene glycol, MTBE, granular urea, polyphenylene, and polyether
imide.
SABIC operates in five business sectors; Basic Chemicals (ethylene,
methanol, propylene, styrene, etc.), Intermediates (industrial gases,
ethylene glycol, ethylene dichloride, caustic soda, etc.), Polymers
(polypropylene, polyvinyl chloride, polyesters, polystyrene, etc.),
Fertilizers (ammonia, urea, phosphates, sulfuric acid), and Metals (long
and flat steel products). Jubail Industrial City is where most of the
operations are located. Not to mention its overseas operations in which
it has 16 affiliated companies which started as joint ventures with Dow
Chemical, Exxon, Mitsubishi, and other major companies worldwide. SABIC
is one of the lowest-cost producers, with the help of subsidized
petroleum from Saudi Arabia. The company has grown into diversified
international operations with more than 9 billion in revenues. SABIC
today is the largest listed company in the Middle East.
1. Hurst Exponent
The first calculation performed was the Hurst Exponent for the
Saudi Basic Industries return from 09/21/2005 to 09/21/2010. The Hurst
Exponent for SABIC was determined for five years (1). For the regression
we utilized t=[2.sup.2], [2.sup.5], ..., [2.sup.10]. Figure 1
illustrates the R/S Analysis for the SABIC daily returns from 09/21/2005
to 09/21/2010. As shown in Table 1, the fractal dimension for SABIC was
1.41693, and the average Hurst was 0.58307. These results suggest
"persistent behavior", or that the time series is trending.
Typically, the larger the H value is, the stronger the trend. Which
signifies that today's events are impacting tomorrow's. Thus,
we have a lengthier memory function in which information can affect the
future for very long periods of time.
[FIGURE 1 OMITTED]
2. Monte Carlo Simulation
Using the Monte Carlo Simulation to test the Hurst exponent of a
random series to which it could be compared, we then produced 10,000
Gaussian random series, each with a period of 1246 values, the
equivalent of five years of trading. The Hurst Exponent was computed for
each series, averaged, and repeated ten times. The mean Hurst was 0.5474
(expected Hurst exponent is close to 0.5) which indicates both a random
series and unpredictability in that time series. This implied that the
SABIC time series was not random.
3. Scrambled Hurst Test
In order to determine if the SABIC time series had a definite
structure for that period, we recalculated the Hurst Exponent after
scrambling the series. This scrambled series, a random sequence, would
maintain the distribution as the original series. The scrambling served
to terminate any underlying structure in the data series.
Table 2 shows that the Hurst Exponent, after the scrambling, is
similar to the generated random series, or 0.5474. We deduced there must
be an underlying structure in the SABIC stock market data for that
particular period.
B. Al Rajhi Bank (1120.SA)
Al Rajhi Bank is the world's largest Islamic Bank and was
founded in 1957. This bank is one of the largest banking corporations in
Saudi Arabia with total assets of SR 172 ($45,867) billions. It has
international presence in countries such as Kuwait, Malaysia, and
Jordan. This bank focuses on Sharia compliant banking and money products
as did Kuwait Finance House.
1. Hurst Exponent
The summary data for the Hurst Exponent for the Al Rajhi return
from 09/21/2005 to 09/21/2010 are enumerated in Table 3.
To calculate the Hurst Exponent for Al Rajhi for five years we
calculated the regression using t=[2.sup.2], [2.sup.5], ..., [2.sup.10].
Figure 2 presents the R/S Analysis for Al Rajhi daily returns from
09/21/2005 to 09/21/2010. Since the fractal dimension was 1.38596, and
the average Hurst was 0.61404, persistent behavior is exhibited. In
other words, information received today continues to be discounted by
the market after it has been obtained.
The Monte Carlo Simulation used before was for comparison purposes,
to scrutinize the Hurst exponent of a random series. Again, we generated
10,000 Gaussian random series, each with a period of 1246 values, the
equivalent of five years of trading. The Hurst Exponent for each series
was determined and averaged then repeated 10 times. The mean Hurst was
0.5474. This indicates the series is random thus implies
unpredictability in that time series. This led us to the conclusion that
the Al Rajhi time series was not random.
[FIGURE 2 OMITTED]
2. Scrambled Hurst Test
To continue our investigation of whether the Al Rajhi time series
has a genuine structure in that period, we scrambled the series, and
then recalculated the Hurst Exponent. Although the scrambled series
preserved the distribution as the original series, the sequence was
still random. Any original structure in the data series would have been
destroyed through scrambling.
Table 4 above shows the Hurst Exponent, after the scrambling,
closely resembled the generated random series, which was 0.56354. Thus
it can be concluded that there necessarily exists an underlying
structure in the Al Rajhi stock market data for the specific period
studied.
C. Etihad Etisalat (7020.SA)
Etihad Etisalat or Mobily (Brand name) is the second
Telecommunications company in Saudi Arabia. The company broke the
nation's monopoly in telecommunications. It was established in 2004
by a consortium led by Etisalat, the UAE based telecom conglomerate.
Mobily was the first Saudi Company to offer 3G services in the Kingdom.
In December 2004, Mobily was listed in the Tadawul Stock Exchange. Today
Mobily has more than 40% of the market share in Saudi Arabia.
1. Hurst Exponent
The summary statistics for the Hurst Exponent of the Etihad Etislat
return from 09/21/2005 until 09/21/2010 are listed in Table 5.
Figure 3 shows the R/S analysis for the Etihad Etislat daily
returns from 09/21/2005 to 09/21/2010, a five-year period. The fact that
the fractal dimension was 1.45411, and the average Hurst was 0.54589
imply a random walk time series. A random walk is characterized by a
lack of correlation between the present returns and the future returns
thus making time series of this type difficult to predict. The mean
Monte Carlo Simulation Hurst was 0.5474 indicating the time series is
random and unpredictable. Thus, the Etihad Etislat time series was
indeed random.
[FIGURE 3 OMITTED]
For SABIC and Al Rajhi stocks, the Hurst exponent results do not
support the EMH, while those of the Etihad Etislat stock do. Table 6
above shows Etihad Etislat with the lowest Hurst exponent of 0.5458
which implies non-predictability for that specific five-year time
series. On the other hand, SABIC and Al Rajhi had higher Hurst values:
0. 0.58307 and 0.61404 respectively, demonstrating persistent behavior.
After testing the reliability of the Hurst utilizing the Monte Carlo
simulation and the scrambled Hurst test, it was found the two stocks had
a fractal nature. This finding was counter to the EMH and the Capital
Asset Pricing Model (CAPM), the Arbitrage Pricing Theory (APT), and the
Black-Scholes option pricing model, which are quantitative models
derived from the EMH. In the literature review it was shown that tests
on market efficiency in the Saudi Arabian market were inefficient. Only
one stock in this study was found to be efficient in that five-year
frame of the time series.
V. CONCLUSION
Our data indicates that there are two Saudi stocks with large Hurst
exponents and one with a low Hurst value among the three major stocks
investigated. These results indicate the markets were not totally random
during the time studied. Clearly, the results do not support the
Efficient Market Hypothesis for the two stocks with high Hurst values.
These stocks were Hurst processes, or biased random walks. Thus, it can
be concluded that some stocks in the market are in fact efficient while
others are not. This is counter to prior studies which indicated that
the entire Saudi Arabian Stock Market was inefficient.
Although the Hurst independent random processes of the Monte Carlo
simulation were about .55, the Hurst exponents of the data sets fell
between 0.54 and 0.61. Al Rajhi, for example, had a Hurst of near 0.61,
which makes it clear that if prices were higher during that time, there
would be about a 61% probability that the stock would rise during the
subsequent period. This is counter to the weak-form efficient market
hypothesis (EMH) assumptions.
This study seeks to remedy the lack of quantitative evidence about
the inefficiency and long-memory bias of Saudi Arabian equity returns.
Preceding analyses found asset pricing theories which postulate that
stock markets are efficient and that stock prices follow a random walk.
It followed, then, that investment models, like modern portfolio theory
or CAPM, assumed asset returns were normally distributed and that the
distribution shape was symmetric. The absence of a normal distribution
or ordinary Brownian motion in the Saudi Arabian stock market may lead
to incorrect asset pricing assumptions and indicate the limitation of
modern asset pricing theories in Saudi Arabia.
This investigation attempted to measure the long-range memory of
the largest MSCI Index stocks in Saudi Arabia. The presence of
long-memory is directly related to the fractal dimension of a time
series. An independent and random process has a fractal dimension of 1.5
and a Hurst exponent of H = 0.5 (Peitgen et al., 1992). Based on the
findings of this study, the following conclusions were drawn.
The Saudi Arabian stock market returns did not comply with the
assumption and properties of a normal distribution in most cases, yet in
a few cases they exhibited characteristics of a normal distribution. Nor
did they conform the weak form of the efficient market hypothesis and
the random walk assumption in most cases. In the absence of a normal
distribution and the random walk assumption, asset-pricing models may
not adequately capture the investment risk and probabilities of equity
returns; one should test the individual stock to determine if it
qualifies as a normal distribution. This is the first time the Saudi
Arabian market has been analyzed for efficiency using the methodology we
incorporated. Traditional tests had assumed a normal distribution but
this was not the case for many financial time series. Our methodology
allowed for power laws, fat tails, and many other forms of distribution.
Finding evidence in this study of long-memory in stock returns
could help investors understand the limitations of traditional asset
pricing models in the region. In this way, investors are in a better
situated to assess the actual investment risk and returns in the Saudi
Arabian stock market.
Despite stock market reforms initiated in 2001, the Saudi Arabian
market is still inefficient and there are many cases of speculative
trading. Regulators should implement major reforms in the regulatory and
transparency aspects of the markets including privatization of the
government ownership in corporations.
Based on these findings, investors should apply asset pricing
models with caution in the markets studied. When there is evidence of
long-memory, the random walk assumption of modern asset price theories
is violated and this additional risk should be figured into
investors' strategies. It is also recommended that investors,
financial practitioners and academicians apply the rescaled range
analysis, and soft computing to financial time series. This study also
shows the greater role of nonlinear asset pricing models in these
markets.
Investors should make themselves and their clients aware of the
distinctive investment risk in the region. The existence of long-memory
in Saudi Arabian equity returns may lead to less than expected
performance of some investment strategies because of inaccurate risk
management.
ENDNOTE
(1.) Hurst measure has been extensively employed by Mandelbrot
(1967, 1968, and 1969).
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Dhari Al Abdulhadi (a) *, Shekar Shetty (b), Mansour Alshamali (c)
(a) Department of Economics and Finance, College of Business
Administration, Gulf University for Science & Technology, Kuwait
(b) University of Dubai, UAE
[email protected]
(c) Insurance and Banking Department, College of Business Studies,
Kuwait Public Authority for Education, Kuwait
* The authors are thankful to Dr. Dilip Ghosh for his constructive
and insightful comments on this paper.
Table 1
Fractal dimension for SABIC
Fractal Dimension 1.41693
Average Hurst 0.58307
Table 2
Scrambled Hurst for SABIC
Scrambled Hurst 0.56290
Standard Deviation 0.040807
Table 3
Fractal dimension for Al Rajhi Bank
Fractal Dimension 1.38596
Average Hurst 0.61404
Table 4
Scrambled Hurst for Al Rajhi
Scrambled Hurst 0.56354
Standard Deviation 0.0414
Table 5
Fractal dimension for Etihad Etisalat
Fractal Dimension 1.45411
Average Hurst 0.54589
Table 6
Summary of all stocks
Stock Average Hurst Fractal Dimension
SABIC 0.58307 1.41693
ALRAGHI 0.61404 1.38596
ETIHAD 0.54589 1.45411