Markets took a negative turn Monday amid the turmoil engulfing Chancellor Angela Merkel in Germany, as it becomes clearer that her coalition government won’t last if she doesn’t address populist concerns on the right.
The crisis in this instance concerns illegal migration. German frustration with Mrs. Merkel’s 2015 open-door policy toward Middle Eastern migrants cost her votes and parliamentary seats in last autumn’s national election. That forced her into months of coalition talks that produced another unwieldy left-right...