Groupon (GRPN -7.8%) closes with big losses. The Street is likely worried about the depressing performance of top rival LivingSocial, something that just forced 29% owner Amazon (AMZN -2.2%) to take a big write-down. In its Q3 10-Q, Amazon noted LivingSocial posted an operating loss of $69M in Q3 on revenue of $124M. Moreover, Amazon now gives LivingSocial a valuation of just $325M, 94% below the $5.7B valuation granted in a Dec. '11 funding round. Groupon, which reports on Nov. 8, is currently valued at $2.66B.