Facebook’s stock plan is bad corporate governance. Do you care?

Facebook wants to make founder and CEO Mark Zuckerberg even more powerful at the social media giant, which is saying something since he already controls 60 percent of shareholder votes.

The Menlo Park company last week said it wants to create a new class of “C” shares that will essentially allow Zuckerberg to sell stock without having to give up his voting power.

So who cares?

That’s not a rhetorical question. I actually want to know if any investor, large or small, cares that Facebook will make Zuckerberg omnipotent for the foreseeable future.

“No one is yelling about (Facebook’s proposal) because the company has been making money,” said Hillary Sale, a professor of law who specializes in corporate governance at Washington University in St. Louis.

Like many Silicon Valley firms, Facebook already boasts a dual-class share system designed to give its founder total control. Facebook sells Class A shares to individuals and mutual funds like Blackrock, Fidelity and Vanguard. But Zuckerberg owns 467.9 million Class B shares, which carry more voting rights.

Under the new plan, Facebook will issue two shares of Class C stock for every share of Class A and Class B. That means Zuckerberg will eventually own 935.8 million Class C shares that he can sell to fund his philanthropic efforts without giving up his valuable Class B stock. The additional shares will also dilute existing Facebook stock, making it less valuable.

“More recently, Mark announced that over the course of his life, he plans to give away 99% of his Facebook shares to advance human potential and promote equality via the Chan Zuckerberg Initiative,” General Counsel Colin Stretch wrote in a filing with the Securities and Exchange Commission. “This too is a long-term engagement that will take many years.

“The board’s proposal will allow Facebook to maintain and improve upon the structure that has served shareholders well, while also enabling Mark to pursue his important goals through the Chan Zuckerberg Initiative.”

From a corporate governance standpoint, the plan is a horrible idea, because it will shield the founder from what little accountability he now faces.

From 2002 to 2012, the number of “controlled” firms — companies with a stock structure that places most of the power in one person or a small group of people — in the Standard & Poor’s 1500 grew from 87 to 114, according to a report by Institutional Shareholder Services, a top proxy advisory service, and Investor Responsibility Research Center. Of the 114, 79 companies featured multiclass stock systems like Facebook’s.

“It’s a troubling trend, one that we are watching,” Sale said.

Research suggests companies that grant stock with more voting power to insiders don’t perform as well over the long term compared with other firms.

“We find that firm value is ... negatively associated with insiders’ voting rights,” a 2007 paper by researchers from Harvard, Stanford and University of Pennsylvania concluded.

Yet sound corporate governance is like hiring a lawyer. You only want it when things go bad. You couldn’t care less when things are going well.

And under Zuckerberg’s leadership, Facebook has been absolutely killing it.

Since going public in 2012, Facebook stock has more than tripled from $38 to $117 per share. A company with almost no mobile presence four years ago reported last week that the monthly number of active mobile users hit 1.51 billion in the first quarter, a 21 percent jump from the same period in 2015.

With Facebook’s performance so strong, it’s no accident that it decided to make this move now.

“Facebook's announcement regarding its C class stock is well-timed,” said Adam Epstein, founder of Third Creek Advisors, a Bay Area corporate governance advisory firm.

My guess is that investors will overwhelmingly approve the plan at the annual shareholders meeting in June. But shareholders should really consider what’s at stake. Yes, Facebook is doing well now, but Zuckerberg is (I think) only human, and like any human, he will screw up. Or get sick and pass away. Or something will happen outside of Zuckerberg’s control that will hurt Facebook.

Take Zynga. Co-founder Mark Pincus owns only 167,589 shares of Class A stock but controls 63.5 percent of the voting power because he owns 72 million Class B shares.

Under Pincus’ leadership, though, the San Francisco firm has been a complete disaster as a publicly traded company. The maker of the once-popular “FarmVille” game on Facebook failed to foresee consumers switching to games played on mobile devices. And Zynga paid $200 million for OMGPop, only to shut it down a year later.

Since 2012, Zynga stock has crashed from $14 per share to less than $3. Yet no one can really do anything, because Pincus effectively has all of the voting power.

Still, Zynga investors essentially agreed to become inferior shareholders, willing to forsake their voting power in exchange for economic benefits.

That sounds fine. As long as there are economic benefits.

“If you don't like the governance, don't buy the stock,” Epstein said.

Thomas Lee is a San Francisco Chronicle staff writer. Email: tlee@sfchronicle.com Twitter:@ByTomLee