Top executives at the world’s largest corporations are using social media more than ever — no surprise there — but Facebook doesn’t seem to be catching anyone’s attention. Like, at all.

A new study from PR firm Weber Shandwick found that CEOs from the world’s 50 most lucrative companies are using Twitter and LinkedIn more than they did two years ago, but have deserted Facebook completely.

The study, which looked at social media use by CEOs running the top 50 companies on Fortune’s 2014 Global 500 rankings list, found that 10 percent of those CEOs are on Twitter, up from just two percent in 2012. LinkedIn was the most popular network, with 22 percent of CEOs on the platform, up from just 6 percent in 2012.

But the study found that none of the CEOs have active, public Facebook pages. In 2012, 10 percent of the CEOs in that category were using Facebook.

Leslie Gaines-Ross, Weber Shandwick’s chief reputation strategist, said that she expects that number to increase in the future (it can’t get any lower) and referred to it as a “blip.”

“There was a sense two to three years ago that CEOs had to be on every platform to be doing their job properly,” she explained. “Now I think that CEOs are identifying which platform really works for them. … I absolutely [see that number going up].”

What’s also a little surprising is that just 28 percent of these CEOs have a public social media account at all, regardless of platform. That number is up — it was just 18 percent in 2012 — but it still seems pretty low considering how widespread social media has become over the past few years.

The study also found that more CEOs are participating in company videos, a nod to the importance of video as a marketing strategy for companies. (As we’ve written here many times, consumer video is on the rise, especially on Facebook.) More than half of these CEOs appeared in videos on their company website or YouTube last year, up from 40 percent in 2012 and just 18 percent in 2010.

The study isn’t perfect, of course. Weber Shandwick looked for CEOs with public, searchable accounts on all of these platforms, but didn’t take into account how frequently they were posting. For example, Berkshire Hathaway CEO Warren Buffett has tweeted just six times since joining the service in 2013.

These CEOs may also be active on Facebook, just not publicly.

It’s also worth noting that those who do post may not be doing it themselves. Gaines-Ross estimated that 40 percent of the CEOs on the list aren’t writing or posting their own content (those who do are almost guaranteed to have a copy editor or publicist reading before hitting send).

And that’s a bummer, because it’s usually more fun (or at least more interesting) when big-time executives manage their own accounts.