** Shares of UK-based Rockhopper Exploration RKH.L down 10.3% at 46.8p
** The oil and gas explorer says Italy has successfully annulled the 190 million euros ($216.45 million) arbitration award previously granted to co in relation to Italy's breach of the Energy Charter Treaty
** Co will no longer receive tranche 2 payment as per the 2023 monetisation agreement from its arbitration against Italy
** Says balance sheet remains robust, having already received tranche 1 payment; intends to claim 31 million euros payout under insurance policy
** Including session gains, stock up ~78%
($1 = 0.8778 euros)
(Reporting by Nithyashree R B in Bengaluru)
((NithyashreeRB@thomsonreuters.com))