amazoncom inc amzn disclosed overnight that it boosted its stake in electricvehicle maker rivian automotive inc rivn to more than 18 and initiated a stake in selfdriving software company aurora innovation inc aur of more than 5 amazon said late wednesday it now owns 162086884 shares of rivian or 181 of the shares outstanding which at current prices would be valued at about 975 billion at current stock prices that would be enough to make the ecommerce giant rivians largest shareholder according to factset ford motor co f is the fifth largest with a 107 stake amazon had owned 158363834 rivian shares as of dec 31 according to a 13f filing also filed late thursday amazon also said it now owned 35239761 or 52 of aurora innovation shares which at current prices would be valued at about 1670 million that would make amazon the thirdlargest shareholder according to factset data behind uber technologies inc uber at 468 and toyota motor corp tm 7203 at 74 rivian shares shed 65 in morning trading thursday and auroras stock lost 37 while amazon shares fell 68 and the sp 500 spx gave up 14