Mumbai: US-based investment research firm Morningstar believes investors may be underestimating the risks of growing concentration in artificial intelligence stocks, said its chief executive officer, Kunal Kapoor."The biggest risk is not that AI fails. It's that investors have become too optimistic about how quickly the benefits translate into company earnings," said Chicago-based Kapoor in an interview during a recent Mumbai visit. "The market is assuming that today's investment spending will eventually translate into stronger revenue, higher margins and better productivity. That may happen, but rarely in a straight line," he said.The concentration of gains in a relatively small group of…