Sky News Business Reporter Ed Boyd says the stock market in America "skyrocketed" about 3 per cent last night.
"It was quite surprising," Mr Boyd told Sky News Australia.
It comes after the US Federal Reserve raised its official interest rates by 0.5 per cent – the highest rate hike in 22 years.
"Normally when interest rates rise, markets fall," Mr Boyd said.
"But that didn’t happen overnight.
"That’s because of the comments made by the Chairman of the US Federal Reserve, Jerome Powell, assuring investors in the market that he wouldn’t be hiking interest rates at a much more aggressive level of 0.75 per cent."