rivian automotive inc stock fell by as much as 18 wednesday to mark its first stumble since it took wall street by storm last week in the year’s biggest initial public offering and one that was among the largest us deals in nearly three decades rivian rivn shares pared some losses and were down 14 at last check that has brought the electricvehicle maker’s valuation to 127 billion down by about 20 billion from tuesday when the stock rallied 15