Silicon Valley experienced a huge earthquake yesterday with OpenAI's ouster of CEO Sam Altman — with the ripples reaching every headline, private group chat, and beyond.

Why it matters: The stunning leadership shakeup raises questions about the organization's future, and the unique structure that gives limited power to even its biggest shareholders.

Catch up quick: On Friday afternoon, OpenAI stunned the world with news that the board concluded that Altman had not been "consistently candid in his communications" and fired him.

• A few hours later, president Greg Brockman announced his resignation given the ouster. He'd earlier been demoted from the board (which he chaired).
• Chief technology officer Mira Murati was named interim CEO while the company conducts a formal search.
• By the evening, three senior researchers reportedly had resigned, according to The Information.

The big question: What exactly happened?

• There are virtually no details from the company, and thus far, public comments from Altman and Brockman have been limited, including a timeline of how they were notified.
• Microsoft — OpenAI's biggest collaborator and investor in its for-profit arm — was blindsided, our colleague Ina Fried reported, learning about the move only a minute before the public announcement. In a statement from CEO Satya Nadella, the company did say it remains committed to OpenAI.

The intrigue: According to journalist Kara Swisher and media reports, a rift had developed within the company's leadership over its tech development vis-a-vis its mission of creating safe AI, leading to the ouster.

Thought bubble: Attracting investors — the primary reason OpenAI created a "capped" for-profit arm in 2019 — requires building a business that keeps creating assets that investors find valuable and potentially profitable.

• Assuming those dynamics are true, it's unclear why the board would be surprised to see Altman push the company in an aggressive direction business-wise.
• But it is a delicate balance to strike, nonetheless.

Meanwhile: This could become egg on Microsoft's face, given how much money the behemoth poured into OpenAI, and how closely it's aligned with its tech.

• So far, Microsoft has reportedly invested $13 billion into OpenAI's for-profit arm, but without a board seat or any other legal mechanism to exercise influence.
• That's also a huge investment into a company that's actually overseen by its nonprofit entity's board — not a group of directors solely focused on shareholder value.

On the flip side: Not finding out about a leadership shakeup until the last minute could be a feature, not a bug.

• Microsoft's deep investment and partnership have enabled it to benefit from OpenAI's tech without having to take responsibility for governance choices or other moves.

Yes, but: Even if Microsoft is fine with the nonprofit, bettering-humanity aspect of OpenAI's structure, venture capitalists paying top dollar for shares in the for-profit arm are, first and foremost, in the business of financial returns.

What's next: Expect some more details to trickle out in the days to come — and perhaps for Altman to reveal the next moves he hinted at in his public statement.

👆 If you need a refresher on OpenAI's structure, here's one.

• And give this more detailed overview on its website a read.

Along with Microsoft, OpenAI's for-profit arm has a number of blue-chip investors, based on news announcements and media reports, but neither of them have any say in its direction. Investors include:

• Sequoia Capital
• Andreessen Horowitz
• Founders Fund
• Thrive Capital
• Y Combinator
• Bedrock Capital
• Tiger Global
• Khosla Ventures

(If we've missed any, feel free to send me a note!)

• These are the people that fired OpenAI CEO Sam Altman (Forbes)
• Microsoft's $13 billion bet on OpenAI carries huge potential along with plenty of uncertainty (CNBC)
• Rogue superintelligence and merging with machines: Inside the mind of OpenAI's chief scientist (MIT Review)

• OpenAI isn't publicly traded (yet), but Microsoft sure is: Note its stock price drop around 3:30pm ET following OpenAI's announcement.