SAN FRANCISCO — Mark Zuckerberg, the co-founder and chief executive of Facebook, announced Tuesday that he and his wife would give 99 percent of their Facebook shares “during our lives” — holdings currently worth $45 billion — to charity.

The pledge was made in an open letter to their daughter, Max, who was born a week ago.

Zuckerberg and his wife, Priscilla Chan, said they were forming a new organization, the Chan Zuckerberg Initiative, to manage the money. “Our initial areas of focus will be personalized learning, curing disease, connecting people and building strong communities,” they wrote.

In a securities filing, Facebook said Zuckerberg planned “to sell or gift no more than $1 billion of Facebook stock each year for the next three years.” He intends to retain his majority voting position in the company’s stock for the foreseeable future.

Earlier this week, Zuckerberg was one of the billionaires who signed on to the Breakthrough Energy Coalition, a group organized by the Microsoft co-founder Bill Gates to contribute toward a multibillion-dollar clean energy fund. The announcement coincided with a Paris summit meeting intended to forge a global accord to cut planet-warming emissions.

Zuckerberg and Chan have recently made visible investments and gifts in several kindergarten-through-high school education projects.

In May, AltSchool, a private school startup in San Francisco that develops personalized learning technologies, announced that it had raised $100 million from a group of investors, including a donor-advised fund financed by the Zuckerbergs at the Silicon Valley Community Association.

In September, Facebook announced that it was working with Summit Public Schools, a charter school network, to develop an on online platform to help tailor education to the needs and interests of individual students.

And in November, EducationSuperhighway, a nonprofit group that helps K-12 schools tap federal funds for high-speed classroom Internet connections, announced that the couple had agreed to donate $20 million to its work.