(Reuters) – Shares of Monitise Plc fell by nearly a third after Visa Inc said it was exploring options for its 5.5 percent stake in the British mobile banking technology company. Visa, the world’s largest credit and debit card company, said it had hired J.P. Morgan Securities Plc to help consider its options for the investment. Monitise was the biggest percentage loser on the London Stock Exchange on Thursday morning, with nearly 250 million pounds ($408 million) wiped off the company’s market value. More than 51 million shares had changed hands by 1008 GMT (6:08 a.m. …