Saverin’s stake is about 4 percent, according to the website Who Owns Facebook. At the high end of the IPO valuation, that would be worth about $3.84 billion. ...Saverin, 30, joins a growing number of people giving up U.S. citizenship, a move that can trim their tax liabilities in that country. The Brazilian-born resident of Singapore is one of several people who helped Mark Zuckerberg start Facebook in a Harvard University dorm and stand to reap billions of dollars after the world’s largest social network holds its IPO. “Eduardo recently found it more practical to become a resident of Singapore since he plans to live there for an indefinite period of time,”Facebook Billionaire Gives Up Citizenship to Escape Bad American Tax Policy: CLICK FOR MORE..