Credit Suisse started its own inquiry, conducted by an outside law firm, which found that the spying had been ordered by the bank’s chief operating officer, Pierre-Olivier Bouée, who resigned in October after the finding. The inquiry found that Mr. Thiam and other executives had not been aware of the surveillance effort.

But the incident was damaging for the bank, which had spent years trying to put its house in order, only to be faced with questions about whether its chief executive was out of the loop on a corporate spying effort and, if he was, what else might be happening under his management that he did not know about.

Before long, more reports about spying emerged in the news media.

In December, the Swiss newspaper Neue Zuercher Zeitung reported that Peter Goerke, a former head of human resources at Credit Suisse, had been followed last February, just before he left the management board. And another former executive, Colleen Graham, said she believed that she had been surveilled in 2017 in retaliation for her stance on an accounting issue, according to The Wall Street Journal.

Another Swiss newspaper, SonntagsZeitung, reported this month that Credit Suisse had spied on Greenpeace after the environmental group disrupted the bank’s annual shareholder meeting in 2017.

The bank declined to comment on Friday on the more recently reported incidents of spying.

The storm of questions put the bank in the grip of a high-powered tussle, as some shareholders threw their support behind the chief executive and demanded the resignation of the chairman, Urs Rohner.

On Friday, Mr. Thiam maintained again that he “had no knowledge” of the spying efforts. “It undoubtedly disturbed Credit Suisse and caused anxiety and hurt,” he said in a statement. “I regret that this happened, and it should never have taken place.”

During his tenure, Mr. Thiam managed to steady profits at the bank, where a drive for revenue at any cost had pushed traders to take outsize positions in risky and hard-to-sell securities. He turned Credit Suisse away from the volatility of its investment bank by embracing its more reliable wealth management division. That strategy appeared to be working: The bank reported a doubling of profit in the third quarter of last year.