By Svea Herbst-Bayliss BOSTON (Reuters) – Barclays PLC has hired an executive from a rival bank for its mergers, acquisitions, activism and ESG advisory group as demand increases from corporate clients for those services. Peter da Silva Vint, an executive director in the shareholder advisory and activism defense group at Moelis & Co, will join Barclays as a director in a few months, a Barclays spokesperson said. Barclays also hired a more junior executive from Citigroup Inc to join the team next month, the spokesperson added. “We are looking to step up our game and broaden our reach so that in…