US billionaire Ken Griffin, the founder of $28-billion Citadel hedge fund, has purchased 3 Carlton Gardens, a 200-year-old home near Buckingham Palace in central London. The 50-year-old, who has an estimated $8.8 billion fortune, paid about £95 million (₹870 crore) for the property. The 20,000 square-foot house is opposite the UK foreign secretary's official residence.