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

Dwi Tjahjo Purnomo

Abstract


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.

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.


Keywords


Indonesian Market ; Random walk;

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References


Aggarwal, D. (2018). Random walk model and asymmetric effect in Korean composite stock price index. Afro-Asian J. of Finance and Accounting, 8(1), 85. https://doi.org/10.1504/AAJFA.2018.10009906

Aggarwal, D. (2019). Do bitcoins follow a random walk model? Research in Economics, 73(1), 15–22. https://doi.org/10.1016/j.rie.2019.01.002

Ali, S., Shahzad, S. J. H., Raza, N., & Al-Yahyaee, K. H. (2018). Stock market efficiency: A comparative analysis of Islamic and conventional stock markets. Physica A: Statistical Mechanics and Its Applications, 503, 139–153. https://doi.org/10.1016/j.physa.2018.02.169

Balsara, N., Chen, G., & Zheng, L. (2007). The Chinese Stock Market: An Examination of the Random Walk Model and Technical Trading Rules. Quarterly Journal of Business and Economics, 46(2), 43.

Barberis, N., Shleifer, A., & Vishny, R. (1998). A model of investor sentiment. Journal of Financial Economics, 49(3), 307–343. https://doi.org/10.1016/S0304-405X(98)00027-0

Brown, S. J., Goetzmann, W. N., & Kumar, A. (1998). The Dow Theory: William Peter Hamilton’s Track Record Reconsidered. The Journal of Finance, 53(4), 1311–1333. https://doi.org/10.1111/0022-1082.00054

Chen, J.-H. (2011). Variance Ratio Tests Of Random Walk Hypothesis Of The Euro Exchange Rate. International Business & Economics Research Journal (IBER), 7(12), 97–106. https://doi.org/10.19030/iber.v7i12.3318

Cowles, A. (1933). Can Stock Market Forecasters Forecast? Econometrica, 1(3), 309. https://doi.org/10.2307/1907042

Daniel, K., Hirshleifer, D., & Subrahmanyam, A. (1998). Investor Psychology and Security Market Under- and Overreactions. The Journal of Finance, 53(6), 1839–1885. Retrieved from http://www.kentdaniel.net/papers/published/jf98.pdf

Darrat, A. F. (2000). On Testing the Random-Walk Hypothesis : A Model-Comparison Approach. The Financial Review 35 (2000) 105-24, 35(318).

Dash, M. (2019). Testing the Random Walk Hypothesis in the Indian Stock Market Using ARIMA Modelling. Journal of Applied Management and Investments, 8(2), 71–77.

Fama, E. F. (1965). Random Walks in Stock Market Prices. Financial Analysts Journal, 51(1), 75–80. https://doi.org/10.2469/faj.v51.n1.1861

Hong, H., & Stein, J. C. (1999). A Unified Theory of Underreaction, Momentum Trading, and Overreaction in Asset Markets. The Journal of Finance, LIV(6).

Huang, C. (2019). US Stock Market Efficiency : EMH or AMH ? Canyu Huang, 76(Icfied), 171–175.

Lawal, A. I., Somoye, R. O., & Babajide, A. A. (2017). Are African stock markets efficient? Evidence from wavelet unit root test for random walk. Economics Bulletin, 37(4), 2665–2679.

Lo, A. W., & MacKinlay, A. C. (2011). Stock Market Prices Do Not Follow Random Walks: Evidence from a Simple Specification Test. In A Non-Random Walk Down Wall Street (pp. 17–46). Princeton: Princeton University Press. https://doi.org/10.1515/9781400829095.17

M.G. Kendall, A. B. H. (1953). The Analysis of Economic Time-Series-Part I : Price. Journal of the Royal Statistical Society, 116(1), 11–34. Retrieved from http://ww.e-m-h.org/KeHi53.pdf

Osborne, M. F. M. (1959). Brownian Motion in the Stock Market. Operations Research, 7(2), 145–173. https://doi.org/10.1287/opre.7.2.145

Rehman, S., Chhapra, I. U., Kashif, M., & Rehan, R. (2018). Are Stock Prices a Random Walk? An Empirical Evidence of Asian Stock Markets. ETIKONOMI, 17(2), 237–252. https://doi.org/10.15408/etk.v17i2.7102

Sadath, A., Hiremath, G. S., & Kamaiah, B. (2012). Do Stock Returns in India Follow a Random Walk? The IUP Journal of Applied Economics, XI(2). Retrieved from http://ssrn.com/abstract=2061110

Sidney, A. (1961). Price Movements in Speculative Markets: Trends or Random Walk? Industrial Management Review, 2(2), 7–26. Retrieved from http://www.citeulike.org/group/2384/article/1204374

Summers, L. H., & Poterba, J. M. (1988). Mean Reversion in Stock Prices: Evidence and Implications. Journal of Financial Economics, 22(1), 27–59.

Working, H. (1934). A Random-Difference Series for Use in the Analysis of Time Series. Journal of the American Statistical Association, 29(185), 11–24. https://doi.org/10.1080/01621459.1934.10502683

Zhang, Y., Ma, F., & Zhu, B. (2019). Intraday momentum and stock return predictability: Evidence from China. Economic Modelling, 76(July 2018), 319–329. https://doi.org/10.1016/j.econmod.2018.08.009

Zhang, Y., Wei, Y., Ma, F., & Yi, Y. (2019). Economic constraints and stock return predictability: A new approach. International Review of Financial Analysis, 63(February), 1–9. https://doi.org/10.1016/j.irfa.2019.02.007




DOI: http://dx.doi.org/10.26623/jreb.v14i1.3170

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