Mark Zuckerberg Mark Zuckerberg and his wife, Priscilla Chan. REUTERS/Stephen Lam

Mark Zuckerberg and his wife, Priscilla Chan, made headlines around the world Tuesday when they not only announced the birth of their daughter, Max, but also that they'd give away 99% of their Facebook stock over their lifetimes.

But this money - a sum that today is worth about $45 billion - won't all go to charity.

As BuzzFeed's Alex Kantrowitz reported, the Chan Zuckerberg Initiative, the organization that the couple's fortune will go to, is structured as an LLC, a limited liability company, not as a nonprofit organization. (A Facebook spokesperson confirmed to Tech Insider that the organization is an LLC.)

The Chan Zuckerberg Initiative, which has a mission of "advancing human potential and promoting equality," will indeed be able to donate to nonprofit organizations. But it will also be able to make investments in private companies.

According to Facebook, profits it makes from any investments it makes "will be used to fund additional work to advance the mission."

The couple will choose where the money goes, but wrote in a letter announcing the organization that "initial areas of focus will be personalized learning, curing disease, connecting people and building strong communities."

"We need to make sure that there are investments in programs that ensure that the future isn't going to be like today," Chan said in a video introducing the organization. "The future is going to be better than today."

In a response to a question from The New York Times' Vindu Goel, Zuckerberg wrote on Facebook that there are two reasons he and Chan decided to start giving away their fortune early on in their lifetimes.

First is that we have a lot to learn and giving, like anything else, takes practice to do effectively. So if we want to be good at it in 10-15 years, we should start now. Second is that any good we do will hopefully compound over time. If we can help children get a better education now then they can grow up and help others too in the time we might have otherwise waited to get started.