Global market gains over the past year were driven by a handful of heavyweight stocks, exposing the narrow breadth of the rally even as major indices scaled record highs. markets Global market gains driven by a few tech and AI-related stocksMajor indices' rallies are highly concentrated, not broad-basedIndian stocks drop, lag global tech rallyDid our AI summary help? While global markets have surged over the past year, a closer look at the data reveals a far more concentrated story than the headline numbers suggest. An analysis of Bloomberg data by Moneycontrol shows that the gains across the world's major indices…