** Shares of medical device maker Guardant Health rise 10.6% to $165.96

** Evercore ISI sees upside to UnitedHealthcare's expanded coverage for Shield, Guardant Health's GH.O blood-based colorectal cancer screening test

** Brokerage says UnitedHealthcare updated its Molecular Oncology Testing medical policy to cover Shield as medically necessary for average-risk colorectal cancer screening

** The policy applies to UnitedHealthcare's commercial and individual exchange plans, with coverage effective August 1

** Evercore ISI says the decision is notable because UnitedHealthcare is covering Shield as a first-line screening option, meaning it can be used without first requiring patients to decline or fail to complete other screening methods

** Brokerage adds that UnitedHealthcare's move could encourage other commercial insurers to provide similar coverage

** As of last close, UNH stock was up ~29% YTD