MarketWatch: A new crop of ultrawealthy have landed on Forbes magazine’s 2015 billionaire list. Among the new arrivals: Evan Spiegel, the 24-year-old co-founder of instant-message service Snapchat. The ride-sharing service Uber now sports a valuation of $41.2 billion, which elevated co-founders Travis Kalanick and Garrett Camp and their first hire, Ryan Graves, to the list. Other tech newcomers included Jan Koum and Brian Acton, co-founders of instant messaging service WhatsApp, and Facebook COO Sheryl Sandberg.