Chief Executive Jamie Dimon; and Ford Motor Co. The Wall Street Journal reported that Dimon has backed out.
And a huge investment conference dubbed "Davos in the Desert", scheduled for later this month, has seen some leading speakers and participants drop out.
Turkey's foreign minister, Mevut Cavusoglu, said Saudi Arabia was not yet co-operating with the investigation - despite a statement from Saudi Interior Minister Prince Abdulaziz bin Saud bin Naif bin Abdulaziz saying they wanted to uncover "the whole truth".
Mr Trump said: "There's a lot at stake".
There have been doubts, however, about how far the USA president is willing to go, given his administration's deep ties to Riyadh.
"There's not enough money in the world for us to buy back our credibility on human rights if we do not move forward and take swift action", Rubio said.
Speaking from his official country residence in Kent, Mr Hunt said: "None of us know what happened but we are all extremely concerned about the stories that have emerged and the country that can help us get to the bottom of this is Saudi Arabia.
That was our first hope, our first hope was that he was not killed, but maybe that's not looking too good... from what we're hearing", Trump told journalists at the White House.
They include using sales of oil and arms, exchange of information between Riyadh and Washington, and a possible reconciliation with regional arch-rival Iran, said the report.
In an interview with "60 Minutes" airing Sunday, President Donald Trump pledged "severe punishment" if the United States concludes that Saudi agents killed Khashoggi, a U.S. resident, and said that the incident is being investigated.
"The Kingdom as the government and people are steadfast, glorious as ever, no matter whatever the pressures and circumstances might be". "He (Trump) will take action".
The Saudis themselves are warning they'll respond to any "threats" against the kingdom.
Pressure has mounted on the WWE to cancel the event, or change the location of it, following the drama that now surrounds the country of Saudi Arabia.
USA lawmakers, for their part, have come out more strongly.
A security personnel looks out from the entrance of the Saudi Arabia's consulate in Istanbul, Sunday, Oct. 14, 2018.
Turkish officials fear Khashoggi was killed and dismembered, allegations Saudi officials call "baseless".
The Sunday statement by France, Germany and the United Kingdom said the countries "encourage joint Saudi-Turkish efforts" and "expect the Saudi government to provide a complete and detailed response".
Now, President Trump is threatening "severe punishment" for Saudi Arabia if suspicions of Khashoggi's murder are confirmed - and Saudis have vowed to retaliate in kind.
Saudi stocks sink as tension with USA escalates over Khashoggi.
The statement was issued as worldwide concern grew over the writer who vanished on a visit to the Saudi Consulate in Istanbul over a week ago.
But the unexplained disappearance of Khashoggi, a former Saudi government adviser turned critic, has already prompted some big-name business partners to cut ties with projects that are central to Saudi's plans of building a modern economy with technology at its core.
Washington Post columnist Jamal Khashoggi, a prominent Saudi government critic, entered the Saudi Consulate in Istanbul on October 2 and then disappeared.
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