How long is the memory of the US stock market?

The Efficient Market Hypothesis (EMH), one of the most important hypothesis in financial economics, argues that return rates have no memory (correlation) which implies that agents cannot make abnormal profits in financial markets, due to the possibility of arbitrage operations. With return rates for the US stock market, we corroborate the fact that with a linear approach, return rates do not show evidence of correlation. However, linear approaches might not be complete or global, since return rates could suffer from nonlinearities. Using detrended cross-correlation analysis and its correlation coefficient, a methodology which analyzes long-range behavior between series, we show that the long-range correlation of return rates only ends in the 149th lag, which corresponds to about seven months. Does this result undermine the EMH?

G7 Stock Markets: Who is The First to Defeat The DCCA Correlation?

Following the methodology of Ferreira and Dionísio (2016), the objective of this paper is to analyze the behavior stock markets in the G7 countries and find which of those countries is the first to reach levels of long-range correlations that are not significant. We carry out this analysis using detrended cross-correlation analysis and its correlation coefficient, to check for the existence of long-range dependence in time series. The existence of long-range dependence could be understood as a possibility of EMH violation. This analysis remains interesting because studies are not conclusive about the existence or not of long memory in stock return rates.

Shopper Centric Category Management in Convenience Stores: a Qualitative Study

The literature shows that category management is an important concept and tool for retailers and suppliers, but that there is a trend to move to a more shopper-centric category management approach, linked to the shoppermarketing approach. However, the knowledge on this issue is scarce on some retailing sectors, like convenience stores. The present study is focused on convenience stores, with the main purpose of finding out to what extent non-major food retailers successfully adopt a shopper-centric category management. The study is relevant in order to evaluate if a more shopper-centric approach is adequate to smaller companies/stores. To accomplish that goal, an exploratory qualitative study was conducted among convenience store retailers and suppliers. Six semistructured face-to-face interviews were conducted with Commercial Directors and Trade Marketing Managers. This data was complemented with thirteen interviews with shopper marketing experts. The data was analyzed using thematic content analysis technique, identifying themes, categories, subcategories, units of meaning and relations. The results revealed that convenience store retailers use some of the principles and techniques of the shopper-marketing and shopper-centric category management approaches, which they do in a non-standardized and non-formal approach or process. Their suppliers (the manufacturers) do it in a more formal and structured manner, probably as a result of previous interaction with major supermarkets chains. Both direct and indirect evidences of a shopper-centric approach were found, which, however, were slight, discrete and not formal.