"We are thrilled to welcome this diverse group of business leaders and philanthropists to the pledge," Buffett said in a statement. "They bring a wealth of expertise to the group. We will learn a lot from their experiences as we collectively aim to inspire one another to earlier and better giving."
Sandberg hasn't revealed the issues she will address with her pledged money, but it is expected that the adamant feminist will focus her contributions on women's issues.
Sandberg is a best-selling author and the creator of LeanIn.org, which encourages women to reach their professional and personal goals through community, education and monthly meet-ups.
Notable deaths of 2014 [PHOTOS]