UnitedHealth Group shares rose roughly 3% in New York trading on 5 Aug., their largest intraday advance in more than a month, lifting other managed-care and pharmacy-benefit managers. The move followed a Wolfe Research report suggesting U.S. regulators may relax the quality-bonus thresholds for Medicare Advantage plans next year, a change that would bolster reimbursement rates and margins for large insurers, according to the note. Trading volumes were also buoyed by unverified social-media speculation that Warren Buffett’s Berkshire Hathaway is accumulating a position in UnitedHealth. Market-data services cautioned that no regulatory filing or credible report supports the claim; quarterly 13F disclosures are due next week. At a UBS-hosted investor lunch a day earlier, Chief Executive Officer Stephen Hemsley told investors the company is taking a “return-to-basics” approach after recent operational setbacks, according to people who attended. Management highlighted opportunities in OptumHealth and artificial-intelligence initiatives while reiterating confidence in long-term growth.