Bank of Montreal had about $180 million in trading losses on a single day in March, a sign of just how risky stocks were as the coronavirus outbreak became a global pandemic.

The loss, disclosed Wednesday in a quarterly presentation, marks the company’s worst trading day in more than a decade.

“On that day, there was significant volatility in the market related to both equity levels, volatility levels and relationships that exist between different reference spots in the market,” Chief Financial Officer Tom Flynn said in an interview Wednesday.

Two-thirds of the trading losses on that day were tied to the firm’s equity-linked note-related business, according to Flynn. The business sells notes to investors that give them returns linked to equities. The other third of the day’s trading losses were from hedging around Bank of Montreal’s derivative book, he said.

In the quarter ended April 30, Bank of Montreal’s trading revenue fell 35 per cent to $321 million, with its equities business showing a $137-million loss for the three-month period. Among Canadian banks that have reported fiscal second-quarter results so far, Bank of Montreal is the only one with a decline in trading revenue for the period.

The company, in its presentation Wednesday, offered an explanation: “In March, markets experienced unprecedented asset price declines, record volatility, extreme liquidity challenges and dislocations, and significant widening of corporate bond spreads. Given certain trading activities and positions, we experienced negative trading revenue during the most volatile days.”

Flynn described the quarter’s trading results as “mixed” with “strong results” in fixed-income, currencies and commodities. For equities, he said, it was a “tougher quarter.”