Washington | The US economy crashed into its first recession in almost 11 years in February, ending the longest expansion since 1854, according to a group of eminent academics who formally define the US business cycle.

Making their surprise announcement well ahead of official confirmation that gross domestic product (GDP) contracted for a second straight quarter – the traditional "technical" definition of a recession – the National Bureau of Economic Research (NBER) said the speed and scale of the COVID-19 shutdown meant it had already happened.