Wealthfront, the robo-adviser that nearly sold to UBS for $1.4b three years ago, has filed confidentially to go public, it announced Monday. The company joins a string of companies testing the 2025 markets, but it's a unique test as Wealthfront advises its customers to have a buy-and-hold mentality, making it potentially the first direct-to-consumer wealth management to try the markets depending on the ultimate timing.