STORY: London's blue-chip FTSE 100 index hit the symbolic 10,000 points marker for the first time on Friday.It's the latest sign of surging stock markets around the world.The British benchmark had a bumper 2025, gaining nearly 22%.That was its best year since 2009, outperforming Europe's broad STOXX 600 index as well as the S&P 500.The gains largely reflect euphoria towards stocks worldwide thanks to a rally in Artificial Intelligence.Although British stock markets are little exposed to the sector.Instead, its biggest gainers in 2025 included miners such as Fresnillo, boosted by surging precious metal prices.Defence firms such as Babcock and Rolls Royce also shone as Europe ramped up defense spending.And banks including Lloyds benefited from still elevated interest rates alongside decent economic growth.The milestone for the FTSE 100 could help boost sentiment towards UK markets.They've been battered in recent years by political instability, post-Brexit uncertainty and concern about high debt.