Editor's Note: This article originally published on July 13, 2017.

In 2006, Warren Buffett famously pledged to give away most of his Berkshire Hathaway stock, saying that the bulk of those holdings would go to the Bill and Melinda Gates Foundation and the rest to the four foundations controlled by his three children.

Since then, Buffett has given away 40 percent of the Berkshire Hathaway shares that he held in 2006, gifts worth about $27 billion. Buffett’s annual gifts to the five foundations, announced this week, were worth a record-breaking $3.17 billion.

Yet, get this: Because of the stunning rise of Berkshire Hathaway’s value over the past 11 years, Warren Buffett is now much wealthier than when he began his epic giving spree. His net worth today stands at $73.1 billion—up from $46 billion in 2006.

In other words, for all his giving so far, Buffett still has many billions left to give—and will ultimately dispose of far more wealth than either he, the Gateses, or his children probably ever imagined would be the case.

Berkshire Hathaway’s value could well decline in coming years. But judging by the fabled history of this company and its stock, the opposite is more likely to be the case—further boosting how much Buffett wealth will go to philanthropy over time.

Why is it worth paying such close attention to this story? Because while many people are under the impression that all of Buffett’s fortune is earmarked for the Gates Foundation, the gifts to his children’s foundations have turned out to be enormous in their own right—and are bankrolling a wide array of grantmaking both in the United States and abroad. This year, according to Forbes, Buffett sent around $2.4 billion worth of stock to the Gates Foundation. The other $800 million or so went to the family foundations—the Susan Thompson Buffett, Sherwood, Novo, and Howard Buffett foundations.

If this ratio of distributions were to hold through the future, along with the current value of Berkshire Hathaway shares, as much as $18 billion would flow to the family foundations.

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These institutions have been giving away much of the wealth that they receive from Warren Buffett every year, as opposed to building up endowments. It’s not yet known exactly how much money the four Buffett foundations gave away last year. But the figure was likely in the vicinity of $1 billion. If those foundations were a single entity, they’d be one of the biggest grantmakers in the world.

The fact that they’re not a single entity is a big part of why this story is so interesting. The three Buffett children—Susie, Howard and Peter—have diverse interests. While the biggest chunk of Buffett family grantmaking moves through the Susan Thompson Buffett Foundation (STBF), which is the largest private funder of reproductive health and family planning globally and is chaired by Susie Buffett, Howard and Peter have also scaled up major foundations with very different goals.

As we’ve often discussed in the past, Howard’s main issues are hunger and food security, which in turn have led him to a range of related areas, such as bringing peace and electricity to the Great Lakes region of Africa. Howard’s foundation is also undertaking one of the biggest “bets” happening anywhere in philanthropy right now, with its $500 million commitment to improving agriculture in Rwanda. Meanwhile, the NoVo Foundation that Peter built with his wife Jennifer has emerged as a top funder for girls and women’s issues—with some especially ambitious work lately to empower young women of color in the U.S.

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And let’s not forget about the Sherwood Foundation, which is based in Omaha and which Susie leads, in addition to serving as chair of STBF. Ever heard of Sherwood? No, probably not. But in 2015, it gave away about as much money as the Rockefeller Foundation, around $150 million. Most of this giving is focused in Omaha and Nebraska, making the Buffetts one of the largest family funders of local causes anywhere in America. That’s a story that one almost never hears about.

A last point: It’s hard to know how this drama of large-scale philanthropy by Warren Buffet is going to play out. At the rate he’s giving away his Berkshire Hathaway shares, it remains to be seen how he’ll make a significant dent in liquidating his fortune anytime soon. But Buffett is now 87 years, so he doesn’t have unlimited time at this point.

It wouldn’t be surprising to see Buffett decide to pick up the pace, especially since some of the goals he cares about most deeply—especially ensuring that women worldwide have access to family planning services—are now at grave risk in the Trump era, with consequences that could reverberate for decades.

Buffett is famous for his bold moves as an investor. Stepping harder on the gas with his giving right now would be a smart one.

Related: Chasm: What Are Funders Doing To Close Big New Gaps in Aid for Family Planning?