When people grew angry over Facebook (NASDAQ:FB) and its scandals, they would often quit and go to Instagram, ignoring the fact that Instagram is owned by Facebook.

But users saw Instagram as different.

It was different because founders Mike Krieger and Kevin Systrom made it different.  The two had sold their company to Facebook in 2012 for $1 billion, before Facebook stock went public. They were considered the “heart and soul” of Instagram.

Well, they’re out.

Their blog post announcing the move had vague talk about exploring their curiosity and creativity. But there are also reports about Facebook taking a more hands-on approach to Instagram, making it part of the general Facebook experience rather than a separate app.

The good-bye blog post didn’t mention Facebook management.

Facebook is Zuckerberg, Zuckerberg is Facebook

Instagram’s founders departing wouldn’t be a bad thing, if Facebook weren’t seen as toxic, and Instagram weren’t seen as the balm keeping the infection at bay.

The Atlantic adds this is just the latest in a series of moves indicating that Facebook wants to make its subsidiaries, well subsidiary. The founders of WhatsApp reportedly left $1.3 billion on the table as they exited last year. Oculus founder Palmer Lucky also left last year.

The pre-market impact of the news was to sink Facebook shares by 2%, a loss of nearly $10 billion, but as of this writing almost all of those losses have been recovered. More important going forward is that this departure now puts pressure on CEO Mark Zuckerberg to make Facebook stock perform.

Zuckerberg’s reputation — and Facebook stock — has been taking repeated hits ever since the scandal of Russian manipulation in the 2016 election broke. The former whiz kid of The Social Network  condemned his own biopic as “hurtful” in 2014 — but now people may believe that the movie’s depiction of Zuckerberg was too kind.

Zuckerberg is now seen as a threat to democracy, a growth-obsessed drone insulated by his own success from the company’s growing image problems. 

Zuckerberg is now said to have “truth problem” — living in a bubble, rejecting complaints, living by the mantra of “move fast and break things.”

One of those broken things today is Facebook, whose traffic is down 50% over the last two years.  Shareholders haven’t noticed because Instagram was picking up the slack. Now that buffer is gone.

Sheryl Sandberg: The Only Remaining Buffer Between Zuckerberg and Facebook Stock

There remains one buffer between Zuckerberg and reality, Chief Operating Officer Sheryl Sandberg.

When Congress called Facebook on the carpet recently, it was Sandberg who went, not Zuckerberg. She reportedly did well. As the New Yorker pointed out, Zuckerberg has never had a job anywhere besides Facebook and often relies on Sandberg to tell him how workplaces are supposed to function.

If Sandberg were to depart it might do serious damage to Facebook’s market cap, which at $477 billion is twice as big as AT&T (NYSE:T), and almost three times bigger than Walt Disney (NYSE:DIS).

What makes Facebook valuable is growth that keeps its data center capital budget paid for with operating cash flow. Facebook had $24 billion in operating cash flow last year, making its $14 billion capital budget eminently affordable.

Facebook is a company that keeps cloud data centers busy without entangling business alliances, and with traffic it doesn’t have to pay for. This makes it the most profitable of the five “Cloud Czars” — Apple (NASDAQ:AAPL), Amazon.com Inc. (NASDAQ:AMZN), Microsoft (NASDAQ:MSFT) and Alphabet (NASDAQ:GOOGL) are the others. Between them these five dominate the global economy with a combined market cap of about $4.2 trillion.

But as I have been writing since March, Facebook stock is the most vulnerable of the czars, and ultimately the cheapest, specifically due to that lack of entangling alliances. It doesn’t sell things, it doesn’t produce content, and it doesn’t re-sell its capacity.

How long can that remain the case is the question Facebook shareholders should be asking. The answer could come as early as October 20, when the company next reports earnings.

Dana Blankenhorn is a financial and technology journalist. He is the author of a new mystery thriller, The Reluctant Detective Finds Her Family, available now at the Amazon Kindle store. Write him at danablankenhorn@gmail.com or follow him on Twitter at @danablankenhorn. As of this writing he owned shares in T, AMZN and MSFT.