A new, first of its kind study tracks the political leanings of CEOs by examining 18 years of political contributions by more than 3,800 CEOs of S&P 1500 companies.

The big picture: The chief executives of America's largest public companies are more than twice as likely to lean Republican in their campaign contributions than to favor Democrats.

Among big energy companies, CEOs' Republican leanings are even stronger: more than 9 in 10 energy CEOs side with Republicans, and none with Democrats.

CEOs' Republican leanings are even stronger: more than 9 in 10 energy CEOs side with Republicans, and none with Democrats. The study, by professors from Harvard Law School and Tel-Aviv University, classifies a CEO as a Republican or a Democrat if they gave at least two-thirds of their campaign contributions to one party or the other. CEOs that distributed their contributions more evenly between the two major parties were classified as neutral.

Why it matters: Money matters in politics — and CEOs wield significant power in America.

The public trusts CEOs more than journalists and government officials, according to a recent Edelman survey, and 84% "expect CEOs to inform conversations and policy debates on one or more pressing societal issues."

more than journalists and government officials, according to a recent Edelman survey, and 84% "expect CEOs to inform conversations and policy debates on one or more pressing societal issues." They sit on presidential advisory committees like President Trump's Strategic and Policy Forum, which included J.P. Morgan's Jamie Dimon and GM's Mary Barra, and Barack Obama's Economic Recovery Advisory Board.

like President Trump's Strategic and Policy Forum, which included J.P. Morgan's Jamie Dimon and GM's Mary Barra, and Barack Obama's Economic Recovery Advisory Board. And they potentially influence how their companies make independent political expenditures, a large and growing source of campaign finance since the Supreme Court's 2010 Citizens United vs. FEC decision.

The other side: CEOs are responsible for maximizing shareholder value, and "some might argue that support for Republicans is consistent with shareholder interests because share value would benefit from the low-tax and deregulatory policies promoted by Republicans," according to the study.

How they did it: Harvard Law School's Alma Cohen and Roberto Tallarita and Tel-Aviv University's Moshe Hazan and David Weiss analyzed the political contributions to candidates, committees, and parties from 3,810 individuals who served as CEOs of companies in the S&P 1500 index between 2000 and 2017.