The billionaire Peter Thiel’s Founders Fund has raised $625 million for its fourth fund — larger than than his first three funds combined. The round, which was heavily oversubscribed, includes many of Founders Fund’s previous backers. The firm says the team will continue to invest in early and mid-stage start-ups across a broad range of sectors, including education, robotics and the consumer Internet. Founded by Mr. Thiel in 2005, the firm is well known for betting on ambitious start-ups that try to tackle macro problems. The firm’s previous investments include Facebook; SpaceX, a spaceship company; and Palantir Technologies, the data analytics company Mr. Thiel co-founded in 2004. He is also a founder of PayPal, the online payments company, and Clarium Capital, a global macro hedge fund. The Founders Fund’s latest round highlights the widening gap in Silicon Valley between the top-performing, or best-branded, firms and the rest of the industry.  There is obviously no cash crunch for Silicon Valley’s 1 percent.  [Dealbook  12/1/11]