We assess the performance and productivity of Islamic and conventional banks usingfinancial ratios, a two- and afour-component meta-frontier Malmquist productivity index (MPI). We focus on the relatively homogenous GCCregion over the 2006–2012 period that covers the globalfinancial crisis. Wefind that Islamic banks exhibit worsecost and profit performance but are on a par with regards to revenue performance compared to the conventionalones. The components of the meta-frontier MPI suggest that the technology of conventional banks improvesmarkedly in years leading to thefinancial crisis and declines thereafter. Islamic banks show a similar but moremuted pattern. By contrast, the pronounced within-Islamic bank group variation in technical efficiency andtechnology suggests that Islamic banks are quite heterogeneous as a group. Overall, the MPI analysis suggests thatthe two bank types are more aligned following the globalfinancial crisis. Policy makers should be wary of theimportant variations within the Islamic banking industry when implementing bank regulations.