On Tuesday, December 1st, Mark Zuckerberg and wife Dr. Priscilla Chan celebrated the birth of their baby girl, Max, by making a stunning announcement; the pair plan to give away 99% of their Facebook shares in their lifetime.

Currently, this is worth about $45 billion.

The announcement was made via Facebook, framed as a letter written by Zuckerberg and his wife to their baby girl. In the letter Zuckerberg laid out his vision in extensive detail about a world he hopes Max will be able to live in. The letter covers Zuckerberg’s passions for giving the world access to the Internet and his belief that this generation could be the one to end world hunger, along with many other initiatives.  The couple stated, “Max, we love you and feel a great responsibility to leave the world a better place for you and all your children.”

They plan to focus on using the money for “personalized learning, curing disease, connecting people and building strong communities.” The pair have created the Chan Zuckerberg Initiative to do this, which Zuckerberg said will “join people across the world to advance human potential and promote equality for all children in the next generation.”

Zuckerberg made his stock giveaway promise official in a filing with the Securities and Exchange commission. For now, Zuckerberg will gift up to $1 billion of his stock for each of the next three years.

This isn’t the first time Mark and his wife have donated to charity before as the pair have already donated $1.6 billion. Back in 2010, Zuckerberg signed the Giving Pledge which meant he committed more than half of his wealth to philanthropy or charity. Zuckerberg is currently the 7th richest person in the world according to Forbes’ Real Time Billionaires ranking, with a net worth estimated at $46.8 billion.

Others are already cheering Mark on for his contributions. Alt School Founder and CEO Max Ventilla thinks $45 billion “is really an enormous amount of money to fuel initiatives that wouldn’t otherwise started.” Others are inspired to give more back, and Daniel Lurie, founder and CEO of the nonprofit Tipping Point Community, hopes this is the start of a new trend. “We have others who can do the same things [as Mark] and we hope they can step up as well”, Lurie said.

More details about the Chan Zuckerberg Initiative will come out over the next few months once the couple returns from maternity and paternity leaves.