SAN FRANCISCO — Mark Zuckerberg and Dr. Priscilla Chan celebrated the birth of a baby girl with the stunning announcement they plan to give away most of their fortune through a new initiative to “advance human potential and promote equality for all children in the next generation.”

Mark Zuckerberg and Priscilla Chan have welcomed their baby girl, Max, into the world. He posted on Facebook, Your mother and I don’t yet have the words to describe the hope you give us for the future.

The billionaire Facebook founder and chief executive and his physician wife pledged to give away 99% of Facebook shares in their lifetime, currently worth about $45 billion, in a letter to their newborn daughter Max posted on Facebook on Tuesday, the national day of giving known as #GivingTuesday.

“Our initial areas of focus will be personalized learning, curing disease, connecting people and building strong communities,” Zuckerberg and Chan wrote to their daughter. “We know this is a small contribution compared to all the resources and talents of those already working on these issues. But we want to do what we can, working alongside many others.”

Facebook’s Chief Operating Officer Sheryl Sandberg commented on Facebook: “This is a beautiful letter and an incredible commitment to future generations.”

The pledge is remarkable given Zuckerberg’s relative youth — he’s 31 — and because he’s still at the apex of his career running Facebook, a prosperous tech giant that powers the world’s most popular social network and boasts a $300 billion market cap.

Facebook said Zuckerberg’s gradual dispersal of Facebook shares would not affect his status as the controlling shareholder of Facebook “for the foreseeable future.” Zuckerberg has committed to disposing of no more than $1 billion of Facebook stock each year for the next three years, Facebook said.

Zuckerberg will continue his role as chairman and CEO “for many, many years,” Facebook said in a statement.

“Mark and Priscilla are early in their careers and will continue to lead active lives — Priscilla as a pediatrician and Founder and CEO of The Primary School, and Mark as the leader of Facebook,” according to the statement. “They have been very fortunate in their work and do not want to wait until later in life to give back. Instead, they believe in pursuing philanthropy concurrently with pursuing their professional careers.”

Zuckerberg and Chan made the surprise announcement after the close of trading. Facebook shares barely budged in after-hours trading.

Zuckerberg and Chan declined an interview request.

The Chan Zuckerberg Initiative follows in the footsteps of the Gates Foundation started by Microsoft founder Bill Gates and wife Melinda Gates and is part of a growing wave of philanthropy from the Facebook generation of entrepreneurs in Silicon Valley. Zuckerberg had already signed The Giving Pledge, a public commitment to give away at least 50% of his or her wealth or more during his or her lifetime or upon his or her death.

He and Priscilla have already donated $1.6 billion to philanthropy including $120 million to support education in underserved communities in the Bay Area, $75 million to San Francisco General Hospital to complete a new trauma center and buy equipment and technology, $25 million to the Centers for Disease Control and Prevention to help stop the spread of Ebola and $100 million to the Newark Public School System.

Philanthropy coming from a tech pioneer so early in his career drew plaudits.

In a statement distributed by Facebook, Bill and Melinda Gates said: “As for your decision to give back so generously, and to deepen your commitment now, the first word that comes to mind is: Wow. The example you’re setting today is an inspiration to us and the world. We can be confident of this: Max and every child born today will grow up in a world that is better than the one we know now. As you say, ‘seeds planted now will grow.’ Your work will bear fruit for many decades to come.”

Warren Buffett, who conceived of The Giving Pledge with Bill Gates whose Gates Foundation oversees it, said Zuckerberg and Chan “are breaking the mold with this breathtaking commitment.”

“A combination of brains, passion and resources on this scale will change the lives of millions,” Buffett said in the prepared statement. “On behalf of future generations, I thank them.”

Zuckerberg announced last month that he would take two months of paternity leave after the birth of his daughter. The announcement set a new precedent for technology chief executives. Facebook has not said who will run the company in Zuckerberg’s absence. Zuckerberg’s daughter Max was born “early the week of Thanksgiving,” Facebook said.

News of the Chan Zuckerberg initiative comes just days after Zuckerberg announced he would team up with Gates to invest in The Breakthrough Energy Coalition, a clean energy fund, that will explore ideas that “have the potential to transform the way we all produce and consume energy.”

A press statement from Facebook says the initiative will fund nonprofit organizations, make private investments and participate in policy debates “in each case with the goal of generating positive impact in areas of great need.”

“Any profits from investments in companies will be used to fund additional work to advance the mission,” the statement says.

Follow USA TODAY senior technology writer Jessica Guynn @jguynn

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