Premarket movers: Mag 7 stocks are mixed: Alphabet +0.5%, Amazon +0.4%, Apple +0.2%, Meta -0.7%, Microsoft +0.8%, Nvidia -0.2%, Tesla +0.7% Alibaba ADRs (BABA) gain 3% as the company is rolling out what it calls China’s most powerful AI chip, an accelerator to compete with Nvidia Corp. GameStop (GME) rises 4% after CEO Ryan Cohen disclosed a $26.4 million stock purchase in a filing with the Securities and Exchange Commission. Grab (GRAB) rises 6% after Chief Executive Officer Anthony Ping Yeow Tan disclosed a $29.9 million stock purchase in a filing with the SEC. Quest Diagnostics (DGX) falls 6% after the Centers for Medicare & Medicaid Services released new preliminary medicare payment rates for lab services. Vicor (VICR) jumps 9% after the power equipment company raised its third-quarter revenue growth guidance, citing royalties from non-exclusive license to Vertical Power Delivery. Viking Therapeutics (VKTX) soars 32% after announcing positive topline results from a study of dosing regimens for maintaining weight loss.