In this articleUNHBRK.ABRK.BWarren Buffett speaks during the Berkshire Hathaway Annual Shareholders Meeting in Omaha, Nebraska on May 3, 2025.CNBC(This is the Warren Buffett Watch newsletter, news and analysis on all things Warren Buffett. You can sign up here to receive it every Friday in your inbox.)UnitedHealth Group shares have soared almost 30% since Berkshire Hathaway's disclosure in mid-August that it had purchased a bit more than 5 million shares between April 1 and June 30.Minutes before that SEC f ...