They also fear retribution from Saudi Arabia, which has shown a penchant for holding grudges.

One talking point among some executives has been Citigroup’s experience in Saudi Arabia. For decades, the bank had a joint venture with the Saudi government, Saudi American Bank. But after the Sept. 11 terror attacks, and a lawsuit by 9/11 victims against Saudi American Bank, Citi decided to sell its stake. The government was furious and made its feeling clear: Several years later, when Citi sought a license to do business in the kingdom, it found the gates closed. It took years of lobbying and trips to Riyadh before Citi gained the license last year.

Despite pleas from corporate leaders for help, Mr. Trump continued to instruct Mr. Mnuchin to attend the conference — while also saying that he would consider “punishing” the country if it was found to have killed Mr. Khashoggi. Saudi Arabia’s combative posture — it said it would “respond to any measure against it with an even stronger measure” — left business leaders worried that their companies could become targets.

And many chief executives took notice of the vindictive nature of the Saudi response to the criticism from Canada this summer over Saudi Arabia’s arrest of human rights activists: The kingdom instructed its investment mangers to start dumping its stakes in shares of Canadian companies, even if the sales would result in losses.

Last week, as Mr. Khashoggi’s disappearance drew headlines, companies began pulling out of the Saudi conference, known as the Future Investment Initiative. The New York Times and CNN pulled out as media partners. Late Thursday, Dara Khosrowshahi, the chief executive of Uber, said he would not attend. His decision was perhaps the most courageous: His company had received a $3.5 billion investment from the Saudi sovereign wealth fund in 2016 and one of his own board members is the head of the fund, which was putting on the conference.

I also had to make my own hard decision. I was scheduled to moderate several panels, like I have done at other conferences. But I chose to end my participation because, quite simply, it was the right thing to do. There was no guarantee that I would have the opportunity to ask tough questions of people in power about Mr. Khashoggi’s disappearance, and my participation, I feared, would be perceived as an endorsement of the kingdom rather than a journalistic enterprise.

So the exodus had already begun before the three financial titans began strategizing over the weekend. In a series of phone calls, Mr. Dimon, Mr. Schwarzman and Mr. Fink scrambled to find a way to gracefully exit the conference — or at least put it off, according to the people briefed on the conversations. Those people spoke on the condition of anonymity because of the business and political sensitivity of the discussions.