Steve Digregorio, portfolio manager at Canoe Financial, says he feels like he has lived two years in the past month. Kurt Reiman, who sets strategy for the Canadian arm of Blackrock Inc., says there’s simply no silver bullet to protect a portfolio from a shock this large. Philip Petursson, chief investment strategist at Manulife Investment Management, is forgetting about numbers and turning to history books for guidance.

One month into an historic rout that has wiped nearly C$1 trillion ($690 billion) off Canada’s S&P/TSX Composite Index, investors are struggling to make sense of what just happened — let alone where we go from here.

The speed of the decline has been staggering. It took just 14 trading days for the benchmark to go from a record close to a