The difference in the drop between UKX and IAS is due to fx. Namely, if you were a British investor that bought an european index ETF before the move, you would

The difference in the drop between UKX and IAS is due to fx. Namely, if you were a British investor that bought an european index ETF before the move, you would have lost on the drop, but would have made some of the money back on the fact that the ETF is denominated in euros, and the euro appreciated against the pound. GBP/EUR dropped by ~5% [1], and a quick calculation assuming a drop of 3% on UKX gives us a loss of 0.97 * 0.95 = 0.9215 which is an ~8% loss on UKX, and is comparable with the loss on the european index. [1] http://finance.yahoo.com/echarts?s=GBPEUR%3DX+Interactive#{%22range%22:%225d%22,%22allowChartStacking%22:true} http://finance.yahoo.com/echarts?s=GBPEUR%3DX+Interactive#{%...