Many investors follow the company's holdings closely because of Buffett's remarkably successful record. Berkshire said Monday that it sold off 36.3 million Apple shares during the third quarter, but the iPhone maker remained Berkshire's biggest single investment worth nearly $114 billion. Berkshire revealed several new investments in pharmaceutical companies made during the quarter, including Merck, Bristol Myers Squibb, AbbVie and Pfizer. The Merck, Bristol Myers and AbbVie stakes are all worth roughly $2 billion apiece, while the Pfizer investment was smaller at roughly $140 million.