What happens to customers if one of the biggest crypto exchanges goes bust?

From the BBC World Service: One of the world’s biggest cryptocurrency exchanges, FTX, is on the brink of collapse. A bailout deal it struck with archrival Binance on Wednesday has fallen through. Plus, a new survey says the influence of fossil-fuel lobbyists at climate talks has risen significantly in recent years. And, the costs of supporting migrants who are rescued at sea.