All the while bolstering its holdings in Apple.According to a regulatory filing, Berkshire cut its position in TSMC, the world's largest contract chipmaker, by just over 86% in the fourth quarter.It comes just three months after the conglomerate unveiled it had bought more than $4.1 billion worth of TSMC stock.Such a turnaround is rare for Berkshire but not unprecedented.TSMC last month said revenue in the first quarter is likely to dip 5% as it weathers a global downturn in the chip industry.Berkshire also divested its shares in some banks,and trimmed some positions across its portfolio of U.S. listed companies.Those to face the chop include Chevron and Activision Blizzard - the maker of the "Call of Duty" video game.Microsoft is trying to acquire the video game maker but is facing regulatory scrutiny.Apple was among Berkshire's few additions, which Buffett views more as a consumer products company. Berkshire bought another 20.8 million shares of the firm worth $3.2 billion.Shares in Apple have surged nearly 18% since the start of the year.