Facebook isn't a kid anymore, and neither is CEO Mark Zuckerberg.

The social network, famously created in a Harvard dorm in 2004, turns 15 next year -- pretty long in the tooth, in Internet years. And an increasing number of its shareholders are saying it's time for Facebook (FB) to grow up.

What does that mean, exactly? If you look at a proposal filed on behalf of several large Facebook shareholders this week, it means forcing Zuckerberg to step down as chairman.

The proposal, which was originally filed in June by Trillium Asset Management, received an extra vote of confidence this week as the state treasurers of Illinois, Rhode Island and Pennsylvania, as well as the comptroller of New York City, officially co-signed the proposal.

These funds are nothing to sneeze at: The NYC comptroller, for example, manages the fourth largest retirement system in the country with over $195 billion in assets; as of the end of July, it owned 4.5 million shares of Facebook, currently worth almost $700 million. And the leaders of those state funds feel it's time that Zuckerberg focus on the task of running Facebook -- and not its board.

It's not the first time that shareholders have proposed splitting the roles; Trillium made a similar proposal in 2016. But in light of Facebook's annus horribilis -- Cambridge Analytica, foreign influence peddling, Congressional scrutiny, hacks and data leaks, a consumer trust problem and now a sagging stock price to match -- it could gain new steam as Facebook tries to stanch the bleeding, and Zuckerberg struggles to manage his empire.

Going beyond the data privacy issues frequently covered by the tech press, the proposal links a wide range of controversies -- from Facebook's detrimental impact on mental health, and discrimination in its ad tools, to its role in spreading violence in Myanmar, India, and South Sudan -- to unchecked power in the hands of Zuckerberg.

"An independent board chair is essential to moving Facebook forward from this mess, and to reestablish trust with Americans and investors alike," said New York City Comptroller Scott M. Stringer.

By way of historical context, it was 20 years ago that Microsoft (MSFT) founder Bill Gates testified before Congress on a federal anti-trust case against the company, and later stepped down as CEO while remaining chairman.

There were unmistakable parallels when Zuckerberg -- another geeky Harvard dropout, and onetime whiz kid turned powerful billionaire -- sat before Congress for a two-day grilling in April 2018 on many of the controversies now cited by shareholders as evidence that it's time to rein him in by splitting the roles. 

And across the tech industry, there are other examples of high-profile companies that ultimately split the roles of CEO and chairman: Microsoft, as well as Alphabet (GOOGL) , Apple (AAPL) , Oracle (ORCL) , Twitter (TWTR) . In total, about 60% of the S&P 500 have split CEO and chairman roles. And while it's relatively uncommon that chairpersons or CEOs are ousted by shareholder vote, it does happen: In 2009 for instance, shareholders forced Ken Lewis, then CEO and President of Bank of America (BAC) , to step down as chairman in the midst of the financial crisis.

"We just think that in general, it's good corporate governance practice to separate the roles of chairman and CEO for mature companies," State Treasurer of Illinois Mike Frerichs told TheStreet.

No one can force Zuckerberg to do anything. Thanks to a tiered stock system that grants him 10 votes for every one by an typical shareholder, he controls 59.9% of Facebook's voting shares. Meanwhile, Facebook's insular boardroom, made up of Zuckerberg, Facebook COO Sheryl Sandberg, early investors Marc Andreessen, Peter Thiel and a few others, is labeled an echo chamber by its critics.

"While ultimately this is up to Mark Zuckerberg to decide, he should look around his peer companies," said Trillium's Jonas Kron.

The proposal is due for a vote in May 2019, and between now and then, the group submitting the proposal will be speaking with other investors, and with Facebook, to make their case for splitting the roles. It may be too soon to say what will happen -- and the proposal could wind up failing -- but there is reason to believe that with share prices sagging under the weight of its many controversies, Facebook might listen to its shareholders.

"When you have these well-respected, influential investors who are responsible for hundreds of millions of dollars asking this question, it's putting the onus on Facebook, and really on Mark Zuckerberg, to justify and explain why he should continue as the chairman," added Kron.

Zuckerberg may have taken the company this far -- but in the eyes of many Facebook investors, nowadays he's hurting more than he's helping. 

(Editor's Pick. This article originally ran on Oct. 18)

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