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SAO PAULO, July 11 (Reuters) - Preferred shares of Brazilian telecommunications firm Grupo Oi SA jumped on Friday as Portuguese lender Banco Espirito Santo calmed investor nerves about potential losses at a web of family-held holding companies behind the bank.
Oi shares have fallen about 20 percent this month on concerns that a planned merger with Portugal Telecom would be jeopardized by the latter's exposure to debt it purchased from a BES-linked firm.
At 10:37 a.m. (1337 GMT), Grupo Oi preferred shares were up 10.56 percent to 1.57 reais. (Reporting by Asher Levine; Editing by Chizu Nomiyama)