The political polling industry is suffering a crisis of credibility after failing to predict Brexit and Donald Trump's victory in the US presidential election. A thorough overhaul of its methods is surely needed.

But in a world where political risk is more potent than ever, investors have little else to go on, and polls still have the potential to trigger considerable market volatility. A prime example this week was France, where polls showed far-right - and anti-euro - candidate Marine le Pen increasing her lead in the first-round presidential vote. The reaction in the credit markets was significant - French sovereign CDS widened from 56bps to 68bps in the space of three days, and is now over 40bps wider than levels reached in the post-Brexit aftermath of September 2016...