Tesla founder and all-around tech visionary Elon Musk made waves earlier this month when he tweeted that he was considering taking the electric car company private.

The tweet, which generated wild trading in Tesla stock and reportedly sparked a federal investigation, illustrates the perils of C-level executives acting on their own on social media.

Social media usage—both for personal and business use—is so widespread that occasional social implosions like the Musk tweet are relatively commonplace. How widespread? eMarketer estimates that roughly nine out of 10 companies use social networks as a marketing tool, and that level of involvement has been steady for years.

But how many C-suite executives have an active social presence, and what are companies doing about it?

Perhaps because social has become the norm, there is little recent data on the matter. In 2016, as an example, Pew Research Center reported that 32% of American workers said their companies had a policy guiding the ways they could present themselves on social media generally. That report was based on a survey from late 2014—truly a different political and social era.

A 2017 report from Weber Shandwick, “Socializing Your CEO IV: The Engagement Factor,” found that half of public CEOs are least visible on social media. But only 38% had posted in the preceding 12 months, and slightly fewer had actually interacted with anyone via social in that time frame.

Also in 2017, a Grisdale Advisors survey of senior executives found that 66% of the 300 respondents polled said that they use social media for professional purposes, and of those, 70% reported posting content on at least a weekly basis.

Interestingly, the Grisdale survey found that Facebook was the social network most widely used for professional purposes—71% of the executives surveyed said they used Facebook that way. LinkedIn was close behind, at 70%, followed by Twitter at 38%.

In the wake of the Elon Musk controversy, it may be time for corporations to dust off those old social media policy guidebooks.