It's been a tough summer for Donald Trump and now even some of his own kind are turning against him. 

The Republican presidential candidate who boasts that his net worth is $10 billion (though others peg it much lower) has gotten a mixed reaction from those in his economic cohort.

Famed hedge fund manager and activist investor Carl Icahn has come out in support of Trump, in April joining him on the campaign trail in celebration of his New York primary victory (no word on whether the $100 million Icahn lost as a result of Trump Taj Mahal's closing has soured the relationship). Venture capitalist and PayPal (PYPL) - Get Report cofounder Peter Thiel was a Trump delegate at the Republican National Convention and spoke at the Cleveland event on the candidate's behalf. Texas oil tycoon T. Boone Pickens has come out in favor of Trump, as has Las Vegas Sands(LVS) - Get Report chief executive and prominent Republican donor Sheldon Adelson.

Others haven't been so vocal about their support for Trump but appear to have helped him to raise money. Fortune reports billionaires John Paulson and Wilbur Ross have hosted fundraisers for him.

But not everyone in the billionaire class is head over heels for the Donald. In fact, many have come out strongly against his candidacy. Here are 11 billionaires who probably won't be clinking champagne glasses from the top of Trump Tower anytime soon. And they make a formidable list of enemies: Their combined estimated net worth is more than $313 billion.

Here they are, in order of ascending net worth. 

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1. Seth Klarman, Net Worth $1.35 Billion

Seth Klarman, the CEO of Boston-based hedge fund the Baupost Group, in an email to Reuterscame out against Trump at the beginning of August.

"His words and actions over the last several days are so shockingly unacceptable in our diverse and democratic society that it is simply unthinkable that Donald Trump could become our president," he said. "I will continue to find ways to support Hillary Clinton and defeat Donald Trump."

What makes Klarman's opposition to Trump perhaps so surprising is that he has, in the past, supported a number of Republicans, including Carly Fiorina, Marco Rubio, Lindsey Graham and Chris Christie (to be fair, he is registered as an independent and has backed Dems, though in lesser numbers, as well).

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2. Tom Steyer, Net Worth $1.61 Billion

Tom Steyer stepped away from his hedge fund, Farallon Capital, in 2012 to delve into politics and, specifically, the environment. And lately, he's taken to going after Trump.

His NextGen Climate Action Committee has released ads hitting Trump. One, titled "Wall," pinpoints Trump's attacks on Mexicans. Another, "Women," highlights his disparaging remarks about women. Both are part of a larger initiative from the group to get out the vote, specifically among millennials.

Steyer also consistently criticizes Trump on Twitter.

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3. Meg Whitman, Net Worth $2.1 Billion

Meg Whitman has not been shy about her disapproval of Trump. She slammed Chris Christie, whose presidential bid she had initially backed, over his Trump endorsement and has made it clear for quite some time she won't be casting her vote for him come November. She has even questioned his business record.

Recently, the Hewlett Packard Enterprise (HPE) - Get Report chief executive and HP Inc. (HPQ) - Get Report chair made her toughest anti-Trump statement yet, via Facebook post.

"Donald Trump's demagoguery has undermined the fabric of our national character," she wrote. "Trump's reckless and uninformed positions on critical issues -- from immigration to our economy to foreign policy -- have made it abundantly clear that he lacks both the policy depth and sound judgment required as President."

Whitman has said she'll be supporting Clinton with her vote and pocketbook instead.

Mark Cuban.

4. Mark Cuban, Net Worth $3 Billion

Mark Cuban has found himself a new hobby in trolling Donald Trump.

The Dallas Mavericks owner and Shark Tank star has roasted Trump on Twitter, questioned his claims of wealth, bashed his business skills, challenged his understanding of the issues and, more recently, called him a "jagoff." He'll also be a judge at the Miss America pageant in Atlantic City this September -- the rival pageant to Miss USA, which Trump previously owned.

The pair used to get along, too.

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5. Stan Druckenmiller, Net Worth $4.4 Billion

Duquense Capital Management's Stanley Druckenmiller has a seat on the #NeverTrump train.

He has given hundreds of thousands of dollars to super PACs backing other Republican White House hopefuls, including Jeb Bush, Chris Christie and John Kasich, and ripped Christie when he endorsed Trump, calling the move "disgraceful."

He said Trump has a "kindergarten-level view of economics" and of China. His conclusion: the GOP candidate "doesn't know what he's talking about."

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6. George Soros, Net Worth $24.9 Billion

George Soros really likes Hillary Clinton, and he's willing to put his money where his mouth is.

The Hungarian-born hedge fund manager has donated millions of dollars to Clinton and other Democratic candidates and causes this election cycle, including pouring several million into Priorities USA Action, the super PAC backing her, and American Bridge 21st Century, an opposition research organization.

He's no fan of Trump, either. During an appearance at the World Economic Forum in Davos, Switzerland, Soros accused Trump and Texas Senator Ted Cruz of "doing the work of ISIS" by stoking fear.

But not everybody in Soros-land hates Trump. The businessman has brought on Steven Mnuchin, who previously worked for Soros Fund Management, to lead his campaign fundraising efforts.

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7. Charles Koch, Net Worth $44.1 Billion

Charles Koch and his brother, David, have for years bankrolled Republican candidates and causes. They're sitting the 2016 presidential election out. One reason: they can't stomach Trump.

At a recent conference hosted by Fortune, Charles Koch made known just how much he dislikes Trump -- and, for that matter, Clinton.

"I see two people that as of this point we're not supporting," he said. "Are you going to put a gun to my head? If I had to vote for cancer or heart attack why would I vote for either?"

He added that Trump's "guiding principles are antithetical" to those Koch believes in, namely, free trade.

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8. Michael Bloomberg, Net Worth $48 Billion

Michael Bloomberg and Donald Trump used to be friends. Not anymore.

The former New York City mayor and business magnate toyed with the idea of making his own run at the White House before deciding against it in March. His reasoning: It could result in a Trump presidency.

Bloomberg had harsh words for Trump while speaking at the Democratic National Convention in July. "Trump says he wants to run the nation like he's run his business. God help us," he said. "I'm a New Yorker, and New Yorkers know a con when we see one."

Not one to stay quiet, Trump hit back at his former pal, staying true to form, with a tweet.

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9. Mark Zuckerberg, Net Worth $53.5 Billion

Facebook (FB) - Get Report founder and CEO Mark Zuckerberg earlier this year issued a harsh critique of Trump without mentioning his name. At Facebook's F8 developer conference in San Francisco, he issued a thinly-veiled warning about the candidate.

"As I look around the world, I'm starting to see people and nations turning inward, against the idea of a connected and global community," he said in prepared remarks about Facebook's 10-year roadmap. "I hear fearful voices calling for building walls and distancing people they label as 'others.' For blocking free expression, for slowing immigration, reducing trade, and, in some cases around the world, even cutting access to the internet."

Despite Zuckerberg's dislike of Trump, the conversation and engagement he's stirring is good for Facebook's business.

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10. Warren Buffett, Net Worth $64.7 Billion

Warren Buffett has made no secret of his support for Hillary Clinton, predicting she'll win the White House and hitting the campaign trail with her.

The Berkshire Hathaway (BRK.A) - Get Report(BRK.B) - Get Report  CEO has dinged Trump, too, at a Clinton rally in Omaha, Nebraska in August challenging the Republican nominee to release his tax returns (he has refused to do so, saying he's under audit).

"Now I've got news for him, I'm under audit too. And I would be delighted to meet him any place, any time between now and the election. I'll bring my tax return, he can bring his tax return. Nobody's going to arrest us, there are no rules against showing your tax returns. And just let people ask us questions about the times that are on there," Buffett said. "You're only afraid if you've got something to be afraid about."

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11. Jeff Bezos, Net Worth $65.9 Billion

Jeff Bezos and Trump probably won't be exchanging holiday cards this December. But the two have traded barbs on a handful of occasions in recent months, ranging from antitrust allegations to suggested trips to space.

Trump has maligned The Washington Post, which Bezos bought in 2013, and accused him of utilizing it to influence policy to Amazon's (AMZN) - Get Report  benefit.

"He's using The Washington Post, which is peanuts, he's using that for political purposes to save Amazon in terms of taxes and in terms of antitrust," Trump said in an interview with Fox News' Sean Hannity in May. He has made similar accusations via Twitter before.

Bezos has defended himself against Trump, saying neither he nor his companies have anything to fear. And the Post has continued its Trump coverage