Bill Gates' private holding company, Cascade Investment, increased its stake in Republic Services (NYSE:RSG) common stock over four consecutive trading days, according to a Form 4 filing. The purchases were made at prices ranging from approximately $213.70 to $217.18. Cascade Investment now holds a 10% stake in the waste management company, and Gates' long-time lieutenant, Michael Larson, also serves on Republic Services' board of directors.