Investigating the weak and semi strong forms of informational efficiency on the West African Economic and Monetary Union’s stock market through returns predictability testsDaouda Lawa Tan TOE, Mamadou TOE, Tibi Didier ZOUNGRANACovid-19 outbreak and stocks return on the West African Economic andMonetary Union's stock market:An empirical analysis of the relationship through the event study approachTibi Didier ZOUNGRANA , Daouda Lawa Tan TOE , Mamadou TOE |