July 13 (Reuters) - JPMorgan Chase & Co reported a big jump in second-quarter earnings on Tuesday as the largest U.S. bank gained from a surge in dealmaking and released more reserves it had set aside last year for potential pandemic-related loan defaults. The bank’s net income rose to $11.9 billion, or $3.78 per share, in the quarter ended June 30, from $4.7 billion, or $1.38 per share, a year earlier. Analysts on average had expected earnings of $3.21 per share, according to Refinitiv. (Reporting by Anirban Sen in Bengaluru and Elizabeth Dilts in New York; Editing by Saumyadeb Chakrabarty) Our Standards: The Thomson Reuters Trust Principles.