https://www.reuters.com/article/rivian-ipo/rivian-valued-at-93-billion-in-debut-after-worlds-biggest-ipo-of-2021-idUSKBN2HV1QG >(Reuters) -Shares of Rivian Automotive Inc opened almost 37% higher in its Nasdaq debut on Wednesday, giving the Amazon-backed electric vehicle maker a market valuation of nearly $93 billion and making it the second most valuable U.S. automaker.