The titans of the technology sector don’t shy away from a political horse race. Here’s a preliminary look at where some of Silicon Valley’s most powerful entrepreneurs and executives are throwing their weight in the 2016 presidential campaign.

Federal Elections Commission filings show presidential candidate Democrat Hillary Clinton has succeeded in snagging support from at least three big names in tech. Meanwhile, members of the tech elite who supported Republican Sen. Marco Rubio’s prior Senate campaign have declined to permit Rubio transfer their past contributions over to his presidential bid.

Clinton’s apparent popularity likely stems from her developing connections in the tech sector over a longer period of time than other Oval Office contenders, according to Mark Schmitt, director of the political reform program at independent think tank New America Foundation.

He said most in Silicon Valley are “fine and comfortable” with Clinton’s policies, but that those policies aren’t their main reasons for giving.

“I think something that’s important to remember is people don’t always give because of a platform. They give because of their friends,” he says.

Republican candidates have been looking to tap into Silicon Valley coffers for a while, says Colby College professor of government Anthony Corrado, who specializes in campaign finance. Platforms centered on easing up business and financial regulations appeal to both entrepreneurs and small-government conservatives. But don't rush to assumptions, Corrado cautions; election season is still in its infancy.

Here's how a few of Silicon Valley's biggest names have directed their political donations so far.

Sheryl Sandberg

No surprises here. FEC records show Facebook Chief Operating Officer Sandberg made a donation of $2,700 to Hillary Clinton’s campaign on April 12, the day Clinton announced her candidacy. The "Lean In" author told Bloomberg in April, “I am very supportive of Hillary Clinton. I’ve said before I’d like to see her as president. And I’d like to see more women presidents all over the world.”

Aaron Levie

You might have heard last month about the Box CEO’s plans to throw a fundraiser for Clinton, a candidate Reuters reported was courting a number of young Silicon Valley executives. Levie made a contribution of $2,700 to the Clinton campaign last month, according to FEC filings.

Levie told Reuters in June that he supported Clinton because of the social policies of her party, such as support for legalizing gay marriage.

“There’s more intersection between the technology industry and policy than ever before,” he also said in an interview with the wire news service.

Elon Musk

The CEO of Tesla Motors and SpaceX made two separate contributions, together totaling $5,000, to the Clinton campaign May 1, according to the FEC. He also received a refund of a $2,600 contribution to Republican Sen. Marco Rubio.

The refund, dated June 12, probably correlates to a contribution to Rubio’s Senate campaign. Politico reported last week that more than 300 donors to the Senate campaign declined to allow transfer of their donations to the presidential campaign.

“There’s probably not too much to be made of this refund activity given the nature of it,” says Corrado.

Mark Zuckerberg

The Facebook founder and CEO appears not to have made a decision about whether and where he might give in the 2016 presidential race. Zuckerberg, like Musk, received a refund of $2,600 in June from the Rubio campaign, according to the FEC. Unlike Musk, the FEC’s records show no sign of a contribution elsewhere.

Zuckerberg has been known to advocate for immigration reform. He met with Rubio in 2013 to discuss the country’s immigration system, months after his political advocacy group funded a television ad supporting a bipartisan solution to immigration reform.

Rubio has said he supports a path to citizenship for undocumented immigrants.

“Zuckerberg is basically saying, ‘I’ll back him as a senator because he’s valuable as a senator, but I haven’t made my presidential decision yet,’ ” Schmitt surmises from the Facebook founder’s recent contribution record. 

Sean Parker

Parker, co-founder of Napster, keeps varied company in the political arena. As Politico reported in April 2014:

"He has met privately in recent months with some starkly different politicians, huddling with both Kentucky Sen. Rand Paul, the libertarian-leaning GOP presidential hopeful, and New York City Mayor Bill de Blasio, the populist progressive Democrat." 

Parker hasn’t made contributions in connection to the 2016 presidential race, FEC filings show and Parker’s office confirmed. Parker was among those to accept a refund from the Rubio campaign in June. A contribution of $2,600 to Republican Sen. Rand Paul in 2014 was for Paul’s Senate campaign, Parker’s office confirmed.

The campaign gifts now listed in the FEC database for the 2016 election may seem small when the salaries and assets of these tech CEOs are taken into account. Individual contributors are permitted to give up to $2,700 per candidate committee per election. In a race that includes a primary election, that means contributors can give up to $2,700 to a candidate for the primary and an additional $2,700 to the same candidate for the general election.

Political action committees, or PACs, face different contribution regulations and file records of contributions with the FEC on a different schedule than presidential campaigns.