Fox News ran 330 stories about Hillary Clinton in 2015. About 300 of them were overtly negative, according to new research.

Fox News may have hit Clinton harder than any other news outlet, but it’s hardly been alone in treating her candidacy with extra scrutiny. Harvard’s Shorenstein Center on Media, Politics and Public Policy released a report this week that says the top news outlets hammered Clinton in 2015 far more than any other presidential candidate.

According to the report, eight of America’s most influential news outlets wrote coverage "negative in tone" about Clinton 84 percent of the time — compared to just 43 percent for Donald Trump, and 17 percent for Bernie Sanders.

In every month of 2015 but one — October, when Clinton was widely praised for her handling of the Benghazi hearings — those eight outlets devoted far more negative than positive coverage to Clinton, the report found:

Of course, that wouldn't be particularly telling in isolation. But the report also found that the media gave Bernie Sanders — on balance — positive coverage in almost every month over the same time period:

The Harvard researchers’ findings match those of Crimson Hexagon, a social media analytics firm in Boston. As we reported in April, Crimson Hexagon, when looking at top-tier news outlets, also found that the media had slammed Clinton more than any other candidate.

The methodology of the Harvard study is different. But it also supports the notion that, if the media has been biased against Sanders, it’s not because they’ve been particularly kind to Clinton.

"Sanders’ media coverage during the pre-primary period was a sore spot with his followers, who complained the media was biased against his candidacy. In relative terms at least, their complaint lacks substance," writes Harvard government professor Thomas E. Patterson in the report.

Why was Clinton’s coverage more negative?

Patterson advances the argument that the negative coverage given Clinton was driven primarily by her strong standing in the primary.

Sanders’s allies and Republicans would probably both dispute that idea. But because Clinton was the frontrunner, Patterson says, she also became easy to mistrust and criticize.

Here’s what he says about frontrunner candidates:

The candidate is typically described as overly calculating and cautious—the implication is that the candidate is withholding something from the voters. And if the frontrunner loses support in the polls—a virtual certainty given the artificial boost that comes from high name recognition in the earliest polls—the narrative tilts negative. The candidate is slipping, which cries out for an explanation of one sort or another, which is always found in soft spots in the candidate’s character, message, or organization and not in the vagaries of polling.

The report says it included hundreds of thousands of posts in its analysis of presidential primary media coverage. (The publications factoring in the analysis were CBS, Fox, the Los Angeles Times, NBC, the New York Times, USA Today, the Wall Street Journal, and the Washington Post; you can read more on the report's methodology here.)

How Clinton's negative coverage reflects the media's positive view of her chances

Sanders's supporters have alleged that the press has unfairly treated the Vermont senator's candidacy, even picketing CNN to protest a "media blackout" of their candidate.

At first glance, this data suggests that they're wrong to complain: After all, it shows that the media has battered Clinton more than any other candidate, perhaps because of the ongoing controversy over her emails.

But the greater scrutiny probably also reflects the fact that the media regards her as a more serious frontrunner than Sanders. And that may really have hurt Sanders's chances as much as — or more than — negative stories.

"If you are portrayed as not having much of a chance to win, studies show voters tend to pick up on that. They echo the opinions of journalists that certain candidates are not worth following," says Bob Lichter, a George Mason communications professor and director of the Center for Media and Public Affairs.

Of course, this cuts both ways. Sanders's fans may have a point when they complain that the press hasn't taken their candidate seriously. But if the media had treated Sanders as a likely winner, it would have almost certainly attacked him more frequently too.

"One of the goals of American journalists is to get out all the information on the person most likely to be president," Lichter says. "As soon as a person moves ahead in the polls, the coverage turns more negative."