Nvidia's ability to maintain its profit margins is uncertain as tech giants build their own chips, ING's Jan Frederik Slijkerman writes in a report. "Major customers such as Microsoft, Alphabet and Amazon are developing their own custom chips to help manage AI infrastructure costs (capex efficiency)," he notes. Therefore, Nvidia's pricing power could face tougher competition than in recent years, which would make it more difficult to keep its current exceptionally high margins over the long term, even as the company expands into new business lines, he says. Nvidia shares are down 1.3% premarket.(najat.kantouar@wsj.com)