Facebook shares: what's behind Mark Zuckerberg's 'hacker philanthropy'?

The tech billionaire was already one of the essential figures of our age. Now, with his $45bn pledge, he's being seen as a generational Superman. But does a state-like level of spending run the risk of making him a 'chequebook dictator'?

Mark Zuckerberg drives a Volkswagen Golf. He pays himself an annual salary of a dollar. In 2006, at the age of 22, he turned down a billion times that for Facebook. In 2010, when his then-girlfriend (now wife) Priscilla Chan moved in to his home, he posted an update offering their crockery and appliances because they had "2x everything". He dresses in grey T-shirts and hoodies.

As quiet a life as Zuckerberg and Chan lead in some respects, they are in others fairly conspicuous. And on Tuesday they took an extraordinary action in the most visible way possible. Via an open letter to their new daughter Max (posted, obviously, on Facebook) the Chan Zuckerbergs announced that they would be donating 99% of their Facebook shares to charity during their lifetime. A missive featuring a bullet-pointed mission statement and the phrase "personalised learning tools" may lack the gooey warmth that little Max might have been entitled to expect, but no one can deny its potential impact: at current values, the family's donation is worth more than $45bn.