Facebook Co-founder Dustin Moskovitz has become the fourth richest person under 40 globally with a net worth of $26 billion, Bloomberg said. The development comes as the shares of his task-management company, Asana, have rallied over 250% since mid-May, valuing his stake at almost $8 billion. The 37-year-old left Facebook in 2008 to co-found Asana with his colleague Justin Rosenstein.