Random Walk Tests for the Lisbon Stock Market

Maria Borges ()

No 2007/14, Working Papers Department of Economics from ISEG - Lisbon School of Economics and Management, Department of Economics, Universidade de Lisboa

Abstract: This paper reports the results of tests on the weak-form market efficiency applied to the PSI-20 index prices of the Lisbon Stock Market from January 1993 to December 2006. As an emerging stock market, it is unlikely that it is fully information-efficient, but we show that the level of weak-form efficiency has increased in recent years. We use a serial correlation test, a runs test, an augmented Dickey-Fuller test and the multiple variance ratio test proposed by Lo and MacKinlay (1988) for the hypothesis that the stock market index follows a random walk. Non-trading or infrequent trading is not an issue because the PSI-20 only includes the 20 most traded shares. The tests are performed using daily, weekly and monthly returns for the whole period and for five sub-periods which reflect different trends in the market. We find mixed evidence, but on the whole, our results show that the Portuguese stock market index has been approaching a random walk behavior since year 2000, with a decrease in the serial dependence of returns.

JEL-codes: G14 G15 (search for similar items in EconPapers)
Date: 2007
New Economics Papers: this item is included in nep-cfn and nep-fmk
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (4)

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Journal Article: Random walk tests for the Lisbon stock market (2011)
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Persistent link: https://EconPapers.repec.org/RePEc:ise:isegwp:wp142007

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More papers in Working Papers Department of Economics from ISEG - Lisbon School of Economics and Management, Department of Economics, Universidade de Lisboa Department of Economics, ISEG - Lisbon School of Economics and Management, Universidade de Lisboa, Rua do Quelhas 6, 1200-781 LISBON, PORTUGAL.
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