scholarly journals An Empirical Investigation of the Random Walk Hypothesis in the Nigerian Stock Market

2021 ◽  
Vol 4 (1) ◽  
pp. 62-77
Author(s):  
DA Kuhe ◽  
J Akor
Keyword(s):  
Random Walk ◽  
Stock Market ◽  
Stock Returns ◽  
Unit Root ◽  
Stock Prices ◽  
Null Hypothesis ◽  
Serial Correlation ◽  
Ratio Test ◽  
Variance Ratio ◽  
Random Walk Hypothesis

The Random Walk Hypothesis (RWH) states that stock prices move randomly in the stock market without following any regular or particular pattern and as such historical information contained in the past prices of stocks cannot be used to predict current or future stock prices. Hence, stock prices are unpredictable and that investors cannot usurp any available information in the market to manipulate the market and make abnormal profits. This study empirically examines the random walk hypothesis in the Nigerian stock market using the daily quotations of the Nigerian stock exchange from 2nd January, 1998 to 31st December, 2019. The study employs Augmented Dickey-Fuller unit root test, the random walk model, Ljung-Box Q-statistic test for serial dependence, runs test of randomness, and the robust variance ratio test as methods of analyses. The result of the study rejected the null hypotheses of a unit root and random walk in the stock returns. The null hypothesis of no serial correlation in the residuals of stock returns was also rejected indicating the presence of serial correlation/autocorrelation in the residual series. The result of the runs test rejected the null hypothesis of randomness in the Nigerian stock returns. The results of the variance ratio test under homoskedasticity and heteroskedasticity assumptions both strongly rejected the null hypothesis of a random walk for both joint tests and test of individual periods. Based on the results of the four tests applied in this study, it is concluded that the Nigerian daily stock returns under the period of investigation do not follow a random walk and hence the null hypothesis of a random walk is rejected. The results of the study further revealed that the Nigerian stock market is weak-form inefficient indicating that prices in the Nigerian stock market are predictable, dependable, consistently mispriced, inflated, liable to arbitraging and left unprotected to speculations and market manipulations. The study provided some policy recommendations

Variance Ratio Test of Random Walk in Indian Stock Market

2015 ◽  
Vol 2 (2) ◽  
pp. 89-107
Author(s):  
Saloni Gupta ◽  
Neha Bothra
Keyword(s):  
Random Walk ◽  
Stock Market ◽  
Stock Returns ◽  
Ratio Test ◽  
Variance Ratio ◽  
Random Walk Hypothesis ◽  
Variance Ratio Test ◽  
Indian Stock Market ◽  
High Degree ◽  
The Relationship

We conduct tests of the null hypothesis of a random walk at the aggregate level of market indices and disaggregate level of individual shares to the Indian stock market over various data periods and a comparison of two sub-periods namely the pre liberalization and the post liberalization period. For this, we use the Lo-MacKinlay (1988) variance ratio test. Although the oldest test i.e. the serial correlation coefficient test is also applied to the same data to establish the relationship between the two tests but its results are not elaborated in this paper. The strength of this paper lies in the voluminous data base and a powerful testing tool that it makes use of. It is observed that the market is highly inefficient at daily returns level, thus imbibing high degree of predictability in stock returns, and even the weekly returns show the existence of trend. Monthly returns, however, support the random walk hypothesis across all periods. Thus it is concluded that further refinement of reform measures is required.

scholarly journals Random Walk Hypothesis for Stock Prices in Fiji

2021 ◽  
Vol 13 (2) ◽  
pp. 79-88
Author(s):  
Janesh Sami
Keyword(s):  
Random Walk ◽  
Stock Market ◽  
Unit Root ◽  
Stock Prices ◽  
Structural Break ◽  
Weak Form ◽  
Efficient Market Hypothesis ◽  
Random Walk Hypothesis ◽  
Augmented Dickey Fuller ◽  
Historical Movement

The main goal of this paper is to investigate the random walk hypothesis in Fiji using monthly data from January 2000 to October 2017. Applying augmented Dickey Fuller (ADF 1979, 1981) and Phillips-Perron (1988), Zivot-Andrews (1992), and Narayan and Popp (2010) unit root tests, this study finds that stock prices is best characterized as non-stationary. The estimated multiple structural break dates in the stock prices corresponds with devaluation of Fijian dollar by 20 percent in 2009 and General Elections in September 2014, which Fiji First Party won by majority votes. The empirical results indicate that stock prices are best characterized as a unit root (random walk) process, indicating that the weak-form efficient market hypothesis holds in Fiji’s stock market. Hence, it will be difficult to predict future returns based on historical movement of stock prices in Fiji’s stock market.

scholarly journals APAKAH SAHAM FARMASI DI BURSA EFEK INDONESIA MENGIKUTI HIPOTESIS RANDOM WALK SAAT PANDEMI COVID-19?

2021 ◽  
Vol 14 (1) ◽  
pp. 18
Author(s):  
Dwi Tjahjo Purnomo
Keyword(s):  
Random Walk ◽  
Unit Root ◽  
Moving Average ◽  
Unit Root Test ◽  
Autoregressive Moving Average ◽  
Ratio Test ◽  
Variance Ratio ◽  
Random Walk Hypothesis ◽  
Augmented Dickey Fuller ◽  
Price Movements

<p><em><span lang="EN-US">Berbeda dengan saham lain yang turun cukup tajam saat dimulainya pandemi Covid-19, pergerakan harga saham farmasi justru mengalami peningkatan. Kenaikan harga saham farmasi sejalan dengan ekspektasi investor terhadap peningkatan permintaan obat dan suplemen kesehatan yang berdampak pada kenaikan harga saham di pasar. Penelitian ini secara empiris bertujuan untuk menguji perilaku rantai jual beli di Bursa Efek Indonesia (BEI) yaitu PT Indo Farma Tbk (INAF), PT Kimia Farma Tbk (KAEF), PT Kalbe Farma Tbk (KLBF), PT Phapros Tbk (PEHA), PT Pyridam Farma Tbk (PYFA), dan PT Tempo Scan Pacific Tbk (TSPC). Secara khusus, penelitian ini menyelidiki apakah akan melaporkan apakah saham farmasi selama Pandemi Covid-19 mengikuti Random Walk Hypothesis (RWH) atau sebaliknya apakah pergerakan harga dapat diprediksi. Data yang digunakan dalam penelitian ini adalah harga penutupan saham harian dari tanggal 2 Januari 2020 sampai dengan 2 Februari 2021. Data dianalisis menggunakan uji Augmented Dickey-Fuller untuk adanya Uji Unit Root, uji Variance Ratio, dan Autoregressive Moving Average. (ARMA). Hasilnya, berdasarkan Uji Akar Unit, semua data stasioner di tingkat. Pengujian lebih lanjut menggunakan Variance Ratio, baik secara stand alone intersep maupun trend dan antar semua data juga tidak bergerak secara acak dan tidak mengikuti Hipotesis Random Walk. Terakhir, dengan menggunakan model ARMA, pergerakan log return saham farmasi di BEI dapat diprediksi.</span></em></p><p><em><span lang="EN-US"><em><span>In contrast to other stocks that fell quite sharply at the start of the Covid-19 pandemic, pharmaceutical stock price movements have increased. The increase in the price of pharmaceutical stocks is in line with investors' expectations of an increase in demand for medicines and health supplements, which will have an impact on the increase in stock prices in the market. This study empirically aims to examine the behavior of the chain buying and selling on the Indonesia Stock Exchange (IDX), namely PT Indo Farma Tbk (INAF), PT Kimia Farma Tbk (KAEF), PT Kalbe Farma Tbk (KLBF), PT Phapros Tbk (PEHA), PT Pyridam Farma Tbk (PYFA), and PT Tempo Scan Pacific Tbk (TSPC). Specifically, this study investigates whether to report whether pharmaceutical stocks during the Covid-19 Pandemic followed the Random Walk Hypothesis (RWH) or vice versa whether the price movements were predictable. The data used in this study are daily stock closing prices from January 2, 2020, to February 2, 2021. The data were analyzed using the Augmented Dickey-Fuller test for the existence of the Unit Root Test, Variance Ratio test, and Autoregressive Moving Average (ARMA). The result, based on the Unit Root Test, all data is stationary at the level. Further testing using the Variance Ratio, both by stand-alone intercept and trend and between all data also does not move randomly and does not follow the Random Walk Hypothesis. Finally, using the ARMA model, the log return movement of pharmaceutical stocks in IDX can be predicted.</span></em></span></em></p>

scholarly journals Adaptive Market Hypothesis: Evidence from the Vietnamese Stock Market

2019 ◽  
Vol 12 (2) ◽  
pp. 81 ◽  
Author(s):  
Dzung Phan Tran Trung ◽  
Hung Pham Quang
Keyword(s):  
Stock Market ◽  
Stock Returns ◽  
Stock Exchange ◽  
Ho Chi Minh City ◽  
Stock Exchanges ◽  
Ratio Test ◽  
Time Varying ◽  
Variance Ratio ◽  
Variance Ratio Test ◽  
The Relationship

This paper aims to test the adaptive market hypothesis in the two main Vietnamese stock exchanges, namely Ho Chi Minh City Stock Exchange (HSX) and Hanoi Stock Exchange (HNX), by measuring the relationship between current stock returns and historical stock returns. In particular, the tests employed are the automatic variance ratio test (“AVR”), the automatic portmanteau test (“AP”), the generalized spectral test (“GS”), and the time-varying autoregressive (TV-AR) approach. The empirical results validate the adaptive market hypothesis in the Vietnamese stock market. Furthermore, the results suggest that the evolution of HSX has served as an important factor of the adaptive market hypothesis.

scholarly journals Testing Weak-Form Market Efficiency of Dhaka Stock Exchange

2015 ◽  
Vol 4 (2) ◽  
pp. 79-90
Author(s):  
Md.‬ Abu Hasan‬‬‬‬‬‬‬‬
Keyword(s):  
Random Walk ◽  
Stock Market ◽  
Stock Prices ◽  
Stock Exchange ◽  
Weak Form ◽  
Jel Classification ◽  
Ratio Test ◽  
Daily Return ◽  
Classification Code ◽  
Augmented Dickey Fuller

Measuring the efficiency of the stock market is an important research topic as there are various implications for investors. This paper investigates the weak form efficiency in the framework of the random walk hypothesis for the stock market in Bangladesh, employing both Non Parametric tests (Runs test and Phillips-Perron test) and Parametric tests (Autocorrelation test, Augmented Dickey-fuller test, and Variance Ratio test). The study uses daily return data for the three stock indices of Dhaka Stock Exchange such as DSI (from 02 January 1993 to 27 January 2013) with a total of 4823 daily return observations, DGEN (from 01 January 2002 to 31 July 2013) with a total of 2903 daily return observations, and DSE-20 (from 01 January 2001 to 27 January 2013) with a total of 3047 daily return observations. The evidence suggests that all the return series do not follow the random walk model, and thus the Dhaka Stock Exchange is inefficient in weak form. Thus, historical stock prices can be used to achieve superior gains from the stock markets in Bangladesh. JEL Classification Code: C22, G10, G14

scholarly journals Testing for efficiency in the Saudi stock market: does corporate governance change matter?

2020 ◽  
Author(s):  
Mamdouh Abdulaziz Saleh Al-Faryan ◽  
Everton Dockery
Keyword(s):  
Corporate Governance ◽  
Stock Market ◽  
Stock Prices ◽  
Hurst Exponent ◽  
Weak Form ◽  
Long Range Dependence ◽  
Informational Efficiency ◽  
Variance Ratio ◽  
Wald Tests ◽  
Random Walk Hypothesis

Abstract We study the informational efficiency of the Saudi stock market (SSM), while accounting for corporate governance change, based on single, multiple, and variance ratio-based WALD tests and runs test. The main findings indicate that when the whole period is considered, the random walk hypothesis is rejected, but when divided into two sub-periods separated by the pre-corporate governance and the period marked by corporate governance change, the analysis demonstrates sub-period improvement in weak-form efficiency for the examined series. Robustness of results is verified by analysis using sector indices, which point to market efficiency. Interestingly, Hurst Exponent estimates evidence long-range dependence which suggests the predictability of stock prices and the prospect of speculative opportunities.

scholarly journals On the Efficiency of Stock Markets: A Case of Selected OPEC Member Countries

2019 ◽  
pp. 75-101
Author(s):  
Ebenezer A. Olubiyi ◽  
Peter O. Olopade
Keyword(s):  
Stock Market ◽  
Stock Returns ◽  
Weak Form ◽  
Nonparametric Tests ◽  
Variance Ratio ◽  
Monthly Data ◽  
Random Walk Hypothesis ◽  
Risk Return ◽  
Stock Market Efficiency ◽  
Opec Member

The study investigates the stock market efficiency of selected OPEC member countries within the context of random walk hypothesis and volatility approaches using monthly data on stock market indices from January, 2005 to April, 2016. Parametric (variance ratio: homoskedastic and heteroskedastic martingale), nonparametric (the Wright ranks and scores) tests and ARCH type estimation are performed. Results of both parametric and nonparametric tests indicate that only Qatar's stock market is weak-form efficient. The volatility results suggest that monthly stock returns of OPEC countries are volatile, with Qatar being most volatile and shocks to volatility of stock returns are asymmetric. The implications of this are that: first, investors should be conscious of these shocks when making risk-return decision of their portfolios; second, the results provide useful information to regulators to enable them develop safeguard mechanisms to shield the market from possible asymmetric information emanating from the participants.

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