Billionaire Warren Buffett, marking 60 years leading Berkshire Hathaway, told shareholders in his annual letter released Saturday that he continues to prefer stocks despite a higher cash position.

The 94-year-old Buffett also acknowledged his advanced age in his annual letter, telling shareholders he now uses a cane and will spend less time fielding their questions at Berkshire's annual meeting in May.

Warren Buffett's latest letter to Berkshire Hathaway shareholders offered reflections on mistakes at the company, its growing cash pile, and outlined a slightly revamped annual meeting set for May.