Vicor surged 14% after raising its third-quarter outlook to sequential revenue growth of more than 20%, up from prior guidance of nearly 10%.
That revised forecast signaled materially faster near-term demand for the power electronics company, driving it to the top of midday movers.
Other notable gainers included On Holding, up more than 10% after setting 2029 targets and a $1 billion buyback, and Grab, up more than 7% after its CEO disclosed buying 10.4 million shares.
Losses were led by Quest Diagnostics and Labcorp, down 5.3% and 3.6%, after CMS said Medicare has been paying 16% more for lab services than private payors and will align most rates.