The martingale hypothesis is tested for 15 European emerging stock markets located in Croatia, the Czech Republic, Estonia, Hungary, Iceland, Latvia, Lithuania, Malta, Poland, Romania, Russia, the Slovak Republic, Slovenia, Turkey and the Ukraine. For comparative purposes, the developed stock markets in Greece, Portugal and the UK are also included. Rolling window variance ratio tests based on returns and signs and with wild bootstrapped <italic>p</italic>-values are used with daily data over the period beginning in February 2000 and ending in December 2009. The fixed-length rolling sub-period window captures changes in efficiency and is used to identify events which coincide with departures from weak-form efficiency and to rank markets by relative efficiency. Overall, return predictability varies widely. The most efficient are the Turkish, UK, Hungarian and Polish markets; the least efficient are the Ukrainian, Maltese and Estonian stock markets. The global financial market crisis of 2007--2008 coincides with return predictability in the Croatian, Hungarian, Polish, Portuguese, Slovakian and UK stock markets. However, not all markets were affected: the crisis had little effect on weak-form efficiency in stock markets located in Greece, Latvia, Romania, Russia and Turkey.
