This paper examines the relationship of multiple currencies, coupled with the Euro, to examine if there is evidence of the return of the Monday effect as a result of the recent global economic crisis. Each currency pair, which consists of the US dollar, Japanese yen, Great British pound, Canadian dollar, and Australian dollar, is compared with the Euro to find evidence to support the presence of the Monday effect. The currency pairs are tested in 1999–2004 as the first time period, again in 2005–2009 as the second time period, and then finally in 2010–2012 as the final time period, which represents the period impacted by the economic crisis. It is the authors' contention that the economic crisis that occurred after 2008 had a significant impact in the currency markets and that the Monday effect has become more pronounced because of a weakening of market efficiency. The results provide evidence that in the 2010–2012 period three currency pairs exhibit a statistically significant Monday effect. This Monday effect was not evident in either the 1999–2004 or the 2005–2009 periods, according to our analysis. This leads the authors to postulate that the economic crisis resulting from the mortgage meltdown has had a statistically verifiable effect on currency markets throughout the world. Copyright © 2015 John Wiley & Sons, Ltd.