While Buffett criticised the current market scenario, his firm Berkshire Hathaway has been pumping up its investments. The company under CEO Greg Abel has been increasing its stake in Google-parent Alphabet, making it one of Berkshire's five largest common stock holdings, led by iPhone maker Apple. Berkshire more than tripled its stake in Alphabet and purchased over $2.6 billion worth of shares in Delta Air Lines after Abel formally took over as chief executive from Warren Buffett at the start of the year.