U.S. couple plans to give away $4 billion-but only to projects that will make 'transformational' changes to society.

<Arnold, it turns out, had accumulated a fortune estimated at $4 billion in the past decade—only a handful of people on Wall Street made more during that time. Although he had not yet announced it, Arnold had decided to give almost all of it away. In October 2012, he closed his hedge fund, Centaurus Energy, and retired. In U.S. history, there may have never been a self-made individual with so much money who devoted himself to philanthropy at such a young age. 


The Arnolds want to see if they can use their money to solve some of the country's biggest problems through data analysis and science, with an unsentimental focus on results and an aversion to feel-good projects—the success of which can't be quantified.

No topic is too ambitious: Along with obesity, the Arnolds plan to dig into criminal justice and pension reform, among others. Anne Milgram, the former New Jersey attorney general hired to tackle the criminal-justice issue, has a name for all this: She calls it the "Moneyball" approach to giving, a reference to the book and movie about how the Oakland A's used smart statistical analysis to upend some of baseball's conventional wisdom. And the Arnolds are in no hurry for answers. Indeed, they believe patience is a key resource behind their giving.>