In the first gesture to fulfil his pledge that he and his wife made last year, Facebook CEO Mark Zuckerberg has sold $95 million of the social networking giant's shares.

According to a US regulatory filing, The Chan Zuckerberg Foundation and CZI Holdings LLC sold Facebook shares worth $95 million before taxes, Forbes reported on Saturday.

"The sales likely netted more than $85 million after capital gains taxes, the report added.

The couple plans to give away no more than $1 billion worth of stock each year through 2018.

Last December, Zuckerberg and his wife Priscilla Chan pledged to donate 99 per cent of their Facebook shares — about $45 billion — to advance human potential and promote equality for children.

Declaring the "Chan Zuckerberg Initiative" as they welcomed their first girl Maxima Chan Zuckerberg, the couple said they have created a new foundation that would initially focus on "personalised learning, curing disease, connecting people and building strong communities".

"As you begin the next generation of the Chan Zuckerberg family, we also begin the Chan Zuckerberg Initiative to join people across the world to advance human potential and promote equality for all children in the next generation," they posted in a 2,200-word letter to their new-born daughter on Facebook.

"We will give 99 per cent of our Facebook shares during our lives to advance this mission. 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," the couple wrote.

Facebook currently has 1.71 billion monthly active users.