New Zealanders in KiwiSaver are urged to stay calm and stay the course as stock markets tumble

There's global uncertainty on the back of US President Donald Trump's sweeping tariffs.

US markets are continuing plummet and the UK's main share index - the FTSE 100 - has had its biggest one-day fall in five years, in the wake of the tariffs

Simplicity chief economist Shamubeel Eaqub says we don't know whether these policies will last the distance.

He says Trump is extremely unpredictable, so it's not certain he will go through with all the tariffs.