Currency crises and structural breaks in autocorrelation on the BRICS’ stock markets

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State University - Higher School of Economics

CURRENCY CRISES AND STRUCTURAL BREAKS IN AUTOCORRELATION ON THE BRICS' STOCK MARKETS We gratefully acknowledge financial support through State University - Higher School of Economics Scientific Fund, grant № 08-04-0043.

G. Smirnova,

O. Saldakeeva,

S. Gelman

Introduction

The phenomenon of positive autocorrelation in daily stock index returns is often viewed as a consequence of stable behavioral patterns of certain investor groups (e.g., [Sentana, Wadhwani, 1992; Koutmos, 1997]). However, such patterns may change due to extreme events, i.e. currency and financial crises, and affect the autocorrelation of returns. Emerging markets have experienced severe crises in a recent decade and are therefore a suitable object to study.

Thus, the focus of the current paper is to identify substantial changes in autocorrelation of BRICs' stock markets index returns after experiencing these failures of financial system (the Asian crisis of 1997-1998, the crises in Russia, Brazil in 1998-1999 and the revaluation of the Chinese yen in 2005). Since all countries considered belong to the group of emerging markets and crises might have contagious effects we expect to reveal the influence of events in one country from the group on the markets in other countries. Studying stock market crises in BRICs and Thailand as possible causes of structural changes on stock markets is contribution of this paper to the existing literature. For this purpose we test for structural breaks in an ARMA-GARCH-model on the commonly known crisis dates.

1. Theory and econometrics

1.1 Autocorrelation

The phenomenon of the stock autocorrelation was thoroughly analyzed by the previous researches. Generally, the trading behavior of different groups of investors does lead to autocorrelation in asset prices. While fundamental trading rules (based on macroeconomic and other indicators that impact on income flow of securities) lead to a liquid and efficient market, the same is not true for technical (based on historical data of indexes' values) rules. Those investors that base their strategy on the trends in past stock prices are called "feedback traders". And their behavior causes an autocorrelation in stock returns. One of the most famous models of feedback trading on the base of CAPM framework was developed by Sentana and Wadhwani (1992).

Feedback traders fall into two groups: "positive" ("negative") feedback traders systematically follow the strategy of buying (selling) after price rises and selling (buying) after price falls. So "positive" feedback traders only reinforce price movements that create trends on the market when prices will continually overshoot the levels suggested by current publicly available information. As the market corrects for this over-reaction in the following trading period, prices tend to move in the opposite direction and thus negative autocorrelation is induced. The opposite situation is true for negative feedback traders who tend to induce positive autocorrelation in stock returns.

According to Sentana and Wadhwani (1992) negative feedback traders dominate at low levels of volatility and positive feedback traders dominate at high levels of volatility. Such theoretical implication makes it reasonable to expect the dominant influence of the feedback traders during the financial crises when volatility of markets is rather high. For example, when before crises we observe negative autocorrelation then during the crises and some time after when the volatility increases there should be only strengthening in the observed level of autocorrelation. If we deal with positive autocorrelation then volatility increase should lessen the level of positive autocorrelation or even cause the change in its sign. crisis stock market autocorrelation

We expect to find changes in autocorrelation after the considered crises that would support the theoretical implications about behavior of different types of investors during the time of increased volatility.

1.2 Methodology

Testing for structural changes has always been an important issue in econometrics. The earliest test is the test in Chow (1960) which is for a single break in a linear model. The idea of treating a break date as unknown goes back to Quandt (1960) who proposed taking the largest Chow statistic over all possible break dates. If the break date is known a priori, then the chi-square distribution can be used to assess statistical significance. Bai and Perron (1998) developed the test for multiple structural changes. Their method is sequential, starting by testing for a single structural break.

In our study a change in autoregressive moving-average model's parameters means change in autocorrelation of stock index returns. We deal with the non-linear heteroscedastic ARMA-GARCH models will be applied to stock indices series. Details concerning modeling are presented in Section "Results". models. Thus we need another statistics than Chow one in order to apply a procedure similar to the procedure suggested by Bai and Perron. The test we apply was suggested by Andrews and Fair (1988) who extended the Chow test for the case of non-linear regressions. The test is the following:

(1)

where l₁, l₂ and l_r are the maximized values of the log likelihood function in the subsamples before and after the considered break date and for the whole sample respectively.

Having 5 dates as possible break dates we test the hypothesis of no structural break on each of the date. Find the most significant one (with the highest LR test value) and then divide our sample into two subsamples. We proceed on each of the subsample till all the dates are checked and all statistically significant breaks are found. Such methodology allows testing each of the date and ranging structural breaks according to their significance. All calculations discussed are implemented in the econometric package EViews 5.

2. Data description

We collect domestic BRIC stock market indexes in local currency: the BOVESPA index for Brazil, the index of the Russian trading system for Russia, the India BSE (100) National index for India and the Shanghai SE Composite index for China.

Returns are proxied by the log difference change in the price index:

R_t = logP_t - logP_t - ₁, (2)

where R_t - return at time t; P_t, P_t - ₁ - value of the stock price index at time t, t - 1. The data were sourced from Datastream. The sample data for each country cover different periods, as whole our sample covers the period from January 1991 through February 2008. From official web-sites of the central banks of each country we sourced information about shocks that propagate in BRIC countries. As a proxy for such shock we choose the date related either to the announcement made by the Central bank about the changes in exchange rate policy or to a banking crisis. Hence we test 5 dates on the existence of structural breaks:

July, 2, 1997 - devaluation of the Thailand Baht; August, 17, 1998 - devaluation of the Russian ruble; January, 13, 1999 - devaluation of the Brazilian real; August, 26, 2004 - Russian banking liquidity crisis; July, 21, 2005 - China revalued its currency by 2,1 % against the US dollar).

For a preliminary analysis of the data, Table 1 (Appendix) provides summary statistics of stock indices returns. As can be seen, the index returns for all countries apart from Russia are positively skewed and have thick tails. The Jarque-Bera test rejects the normality hypothesis, this is a common feature of all financial data. The magnitude of average returns and standard deviation are quite similar and don not differ substantially. The first order autocorrelation с is not high for the stock indexes of all countries.

3. Results

3.1 ARMA-models Details on results of optimal models estimation are available upon request.

In order to define an adequate ARMA-model of daily returns of the BRIC's countries we apply the Box-Jenkins procedure. The optimal models of the same type for daily returns in India and Brazil during the whole period (from 1 Jan. 1992 for Brazil, from 1 Nov. 1993 for India, to 14 Feb. 2008 for all countries) contain one autoregressive component of lag one (see Table 2, Appendix). The optimal model for Russia (estimation period is from 9 Jan. 1995 to 14 Feb. 2008) contains one moving average component of lag one and the better fitted model for daily returns in China (estimation period is from 1 Feb. 1991 to 14 Feb. 2008) consists of only autoregressive part with lags one and two. For modeling variance we employ the most widely used GARCH(1,1) model thanks to its accuracy and simplicity.

We suggest market frictions as a possible explanation for dependence on daily returns of BRIC's stock markets. Like many emerging markets BRIC's stock markets also suffer from unsatisfactory corporate governance, market manipulation, insider trading and numerous infrastructure problems.

3.2 Identifying structural changes

Structural breaks were exogenously detected by means of methodology described before. The search for structural breaks in each time series detected various number of changes in autocorrelation (see Tables 3-6, Appendix). For Brazil, India and China the detected structural breaks in 1997 for the stock markets of these countries are very significant. As a result of the event in 1997 daily autocorrelation for the Brazilian stock market come down by two times, for Chinese one moving average coefficient also sharply decreased while the second one became insignificant. For these markets changed coefficients become insignificant that may indicate changes in the optimal model for daily returns of the stock markets after the financial turmoil. This only strengthens our supposition about the fact that financial distress leads to structural changes and moreover can change the law of stock prices movement.

As for the Indian daily returns here we detected some reversal pattern in changes of the autocorrelation coefficient: it doubled and remained significant at 5 % level. As a result of the Russian turmoil autocorrelation coefficient for the Indian stock market has decreased from 0,16 to 0,092 and remained significant. The interesting phenomenon is the absence of the influence on the other countries in BRIC group. After the Brazilian currency crisis autocorrelation of daily returns for the Brazilian market decreased by four times, for the Russian stock market the moving average parameter significantly decreased from 0,109 to 0,083 and remained significant.

The Russian banking crisis in 2004 caused decrease of the moving average parameter from 0,083 to 0,038 on the Russian market. Finally, the currency devaluation in China in July 2005 that led to structural change on this market was marked by the fact that autocorrelation coefficients became negative and lost their significance. In all cases the high values of the likelihood ratios indicate significance of all break points.

Significant decrease in the value of autocorrelation coefficients nearly in all cases (exception is the Indian case during the Asian turmoil) and partial changes of the signs from positive to negative can be explained by the feedback trading behavior of investors as a result of an extraordinary event. Also there is some empirical evidence that during the Asian and the Russian financial crises in 1997 and 1998 respectively emerging as well as mature stock markets' investors show a pronounced positive feedback trading pattern. In line with our results there are some similar previous findings for other countries. Bohl and Siklos (2004) argued that negative feedback trading is dominated on the emerging stock markets.

However, crises can cause changes in feedback trading making some type of this trading more significant. For example, Kim and McKenzie came to a conclusion that lower levels of conditional autocorrelation in returns are associated with the increased presence of international investors and the nature of the relationship may change over time. This is consistent with the fact that international investors are positive feedback traders. Koutmos (1997) (for Australia, Belgium, Germany and Japan) as well as Wadhwani (1992) (for the US market) that found out positive feedback trading is more intense during market declines. These findings support the explanation of our results that positive feedback traders' impact increased during and after the crisis that leads to the decline in autocorrelation of stock returns. However, such conclusions should be supported by robust tests. For instance, special tests on the presence of positive/negative feedback traders could be run and this can be a field for further research.

Conclusion

The purpose of this paper was, first, to test our hypothesis whether financial crises could lead to structural breaks in autocorrelation of stock index returns in emerging markets on the example of the 1990s' financial crises. Second, we were to show whether the changes in autocorrelation corresponds to proposed in literature [Koutmos, 1997; Bohl, Siklos, 2004; Sentana, Wadhwani, 1992] reversals of investors' behavior around extreme events.

Using algorithm similar to Bai and Perron (1998) and applying test suggested by Andrews and Fair (1988) we get results that are surprising in some sense. Our analysis revealed that Thailand crisis caused the structural breaks of the highest significance on the Indian and Chinese stock markets. This result contradicts the common fact that India and China were relatively unaffected during and after the Thailand crisis. And also August, 17, 1998 stands for the 2^nd significant break in India. For Russia the test shows that the floating of real in January, 1999 in Brazil led to the structural break on the Russian stock market.

As it was expected, the Brazilian currency crisis induced breaks on the Brazilian stock market, revaluation of currency in China caused structural change on its market, and local banking crisis in Russia led to breaks on the Russian stock market. The latter were also brought about by the 1997th Thai crisis. Thus general conclusion is financial crises that took place in one of the emerging BRIC markets might lead to structural changes in autocorrelation of stock returns in other markets that supports the idea of common investors and high markets interdependence.

On the full sample all series reveal positive autocorrelation that supports the idea about the dominance of negative feedback traders on the emerging stock markets [Bohl, Siklos, 2004]. In most cases structural changes in the autocorrelation due to crises can be explained by the feedback trading theory: higher volatility during crises periods leads to the change in proportion of negative and positive traders in favor of the latter that in turn causes the decrease of autocorrelation.

The origins of autocorrelation changes should be elaborated further with more sophisticated econometric tests on endogenous structural breaks as well as through testing presence of feedback trading on the markets considered. This will be the focus of our further research.

References

1. Andrews D.W.K., Fair R.C. Inference in Nonlinear Econometric Models with Structural Change // Review of Econometric Studies. 1988. Vol. 55. № 4. Р. 615-639.

2. Bai J., Perron P. Estimating and Testing Linear Models with Multiple Structural Changes // Econometrica. 1998. Vol. 66. № 1. Р. 47-78.

3. Bohl M.T., Siklos P.L. Empirical Evidence on Feedback Trading in Mature and Emerging Stock Markets. Quantitative Finance Research Centre, University of Technology, Sydney. Research Paper Series. № 137.

4. Chow G.C. Tests of Equality Between Sets of Coefficients in Two Linear Regressions // Econometrica. 1960. Vol. 28. № 3. Р. 591-605.

5. Gelman S., Burhop C. Taxation, Regulation, and the Information Efficiency of the Berlin Stock Exchange, 1892-1913 // European Review of Economic History. 2007. № 12. Р. 39-66.

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7. Quandt R. Tests of the Hypothesis that a Linear Regression Obeys Two Separate Regimes // Journal of the American Statistical Association. 1960. № 55. Р. 324-330.

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Appendix

Table 1. Descriptive statistics of daily stock market indices

Table 2. Estimates of ARMA-models

Asymptotic standard errors are in parenthesis. Each model presents an iteration of Box - Jenkins procedure. Q-statistics are reported for twenty lags. Values marked with ^***, ^** and ^* are significant at 1 %, 5 % and 10 % level respectively.

Table 3. Russia, ARMA(0,1) - GARCH(1,1)

Source: Own calculations.

Table 4. Brazil, ARMA(1,0) - GARCH(1,1)

Table 5. India, ARMA(1,0) - GARCH(1,1)

Source: Own calculations.

Table 6. China, ARMA(2,0) - GARCH(1,1)

Source: Own calculations.

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