Warren Buffett's Berkshire Hathaway has revealed that it purchased billion-dollar stakes in telecom company Verizon and oil company Chevron and cut its holding in Apple last year. Berkshire's stake in Verizon was valued at $8.6 billion at the end of 2020 and $4.1 billion in Chevron. The iPhone maker remained its largest single stock holding valued at about $120 billion.