Around 15 banks are likely to join the underwriting group, some as early as next week. The consortium buying Electronic Arts Inc. is set to add more than a dozen banks to its underwriting group after JPMorgan Chase & Co. put up $20 billion of debt to bankroll the leveraged buyout. Most Read from Bloomberg The deal, orchestrated by the buyers of the video-game maker — private equity firm Silver Lake Management, Saudi Arabia’s Public Investment Fund and Affinity Partners — would shift some risk off of JPM ...