** Shares of health insurer UnitedHealth Group UNH.N rise 6.3% to $446.20 premarket

** Co raises its 2026 profit forecast on tightened spending on medical costs and improved operating income in its Optum health services business

** Co now expects 2026 adjusted profit per share of $19.50 to $20.00, analysts expect profit of $18.47 per share, per LSEG data

** Co reports Q2 adj. profit of $6.38 per share vs estimates of $4.90 per share

** Q2 operating income for its Optum unit increased 29% to $4 billion

** Up to last close, stock up 26.78% YTD