Jamie Dimon, Chairman and CEO of JPMorgan, is the biggest name in global banking. He has a hotline to world leaders, and what he says matters. In a wide-ranging Big Boss Interview with BBC Business Editor Simon Jack, he shares his concerns about a frothy market fuelled by money boarding the AI hype train. He also admits that the USA has become a less reliable partner due to President Trump’s use of tariffs, but says NATO is a stronger force thanks to the current administration. However, he warns that the war in Ukraine has changed the world.

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