Megadonors like Ken Griffin, Peter Thiel keep their wallets closed for Trump

Four years ago, hedge-fund founder Ken Griffin and his wife donated $1.55 million to a political action committee supporting Mitt Romney , then the Republican presidential nominee.

Late in 2011, Romney visited the Chicago headquarters of Griffin's firm, Citadel (Grey Market: CDFT), and spoke to employees. Perhaps inspired by the gathering, dozens of Citadel workers ultimately contributed to Romney's bid for the White House.

This year, Griffin has given generously to a host of political groups, including some supporting Republican primary candidates Marco Rubio and Jeb Bush , some opposing wasteful government spending, and some supporting GOP candidates in the House and Senate.

He's the 14th-biggest political donor this cycle, according to data sorted by the Center for Responsive Politics and based on filings made through early September. But since Hillary Clinton and Donald Trump have materialized as the major-party candidates in this fall's general election, Griffin has been notably absent from the presidential race.

Welcome to the financial sidelines of the 2016 election, where megadonors like Griffin, Paul Singer, Sheldon Adelson and Richard Uihlein have so far been warming seats. Typically conservative-leaning, some of big business' most prominent political donors appear to be abandoning this presidential race altogether, focusing instead on down-ballot contenders whose victories will affect the balance of power on Capitol Hill.

Peter Thiel , the Silicon Valley entrepreneur, is a prime example: Despite urging Americans to vote for Trump at the Republican National Convention, he has yet to give the real-estate mogul a single dollar.

Instead, Thiel has given money to an Arizona sheriff running for the House, a Tennessee Republican House hopeful who was defeated in his primary, and the California state GOP, among others. A Thiel spokesman said in August that he had no plans to donate to Trump, without offering an explanation. Neither Thiel nor his spokesman immediately responded to a request for comment Friday.

There's a logic to the down-ballot strategy, especially for those who consider Trump's chances of winning the presidency low. Among the big donors, "to the extent that their interests depend upon laws passing ... holding Congress is at least as important as the presidency," said Michael Malbin, a political science professor at the State University of New York in Albany.

But for some of the sideliners, there are also practical concerns. Many believe that Trump, who is prone to mercurial rants and bullying, lacks the temperament for high office, and he isn't above bashing detractors on Twitter, a prospect that the more guarded Wall Street money managers find appalling.

More critically, Trump's anti-trade stances, which include promises to roll back the Trans-Pacific Partnership, to impose steep tariffs and to penalize U.S. companies that move operations to Mexico, concern many economists.

Clinton, on the other hand, espouses a platform of tighter regulations that rankle some financial and corporate executives. She wants to broaden the reach of Dodd-Frank , the landmark 2010 financial-regulation law, reduce tax advantages for activist investors, which would affect some major hedge funds, and lengthen the time frame under which prosecutors can pursue financial crimes.

In a late June interview with CNBC, Elliott Management founder Singer, who has indicated opposition to both Clinton and Trump, caused a stir by saying that Trump's protectionist trade policies were "close to a guarantee" of a future "global depression."

By that point, Singer had contributed millions of dollars to various political groups this cycle, including at least $5 million to a PAC supporting Rubio — a significant chunk of his $17.3 million in overall spending this election cycle, which makes him the fourth-biggest donor of either political persuasion, according to CRP figures. But after Rubio dropped out of the race, Singer's spending focused on conservative House and Senate candidates, supporting gay rights and other issues.

At CNBC and Institutional Investors' "Delivering Alpha" conference last week, Singer was more reserved. "I don't want to speak about politics at this juncture," he said. Still, he couldn't resist a veiled jab at a recent fainting spell that had afflicted Clinton. "In two months or so, we'll know the answer to … which envelope," he said, "if both of these people are still on the stage at that time." An Elliott spokesman declined to elaborate on Singer's current political thinking for this article.

Other fence sitters have been even more reserved.

Griffin, who has given a total of $10.6 million to various groups this cycle, according to a spokesman, has avoided discussing the presidential campaigns. In an e-mail to CNBC, he emphasized his support for Republican House Speaker Paul Ryan, who is running for re-election.

"Speaker Ryan's vision for a confident America, both at home and abroad, reflects his thoughtful leadership" on topics like national security and alleviating poverty, Griffin wrote. "I am supporting many Republican candidates who embrace the principals and policies set forth in Speaker Ryan's vision and who are committed to moving our country forward on the right path."

A Citadel spokesman noted that in addition to the support Romney received from Griffin and other employees 2012, President Barack Obama received financial support from a number of Citadel workers, including Griffin, during his first bid for president. The spokesman added that employees aren't encouraged or discouraged in making political donations, all of which are vetted.

Adelson, the Las Vegas casino magnate who along with his wife was the single-biggest spender during the 2012 election cycle, is another megadonor who has been surprisingly reserved in recent months. He initially endorsed Trump for president, praising him in a May Washington Post op-ed column, and reportedly promised $100 million or more to Trump's campaign around that same time. But that money never materialized.

On Sept. 19, CNN reported that the Adelsons would give just $5 million to Trump, through a PAC called Future45 designed not explicitly to aid the Republican contender, but to help defeat Clinton. (During the primary season, Singer and Griffin also gave money to Future45.) The vast majority of Sheldon and Miriam Adelson's planned political spending, $40 million in total, is reportedly now earmarked for down-ballot Republican candidates. A spokesman for the businessman said the Adelsons don't comment on political matters.

Uihlein, the billionaire founder of the packaging and shipping company Uline Inc., is the sixth-largest political donor this cycle, with about $13.6 million in donations, according to CRP's numbers. But the vast majority of his money has been routed to PACs supporting down-ballot candidates and the Republican National Committee.

He's also given millions to the Club for Growth, which has been skeptical of Trump, and a PAC called Our Principals, which was formed to undermine Trump's bid for president (but is no longer active, according to an official there). Interestingly, though, Uihlein also gave $5,400 to the Trump campaign in late July — about 4 percent of his overall giving and the maximum hard-money contribution. He did not respond to messages requesting comment.