London: Boeing Co. shares sank after the UK said it would halt flights of the 737 Max and Germany and Ireland followed suit.

Europe’s aviation regulator prepared a similar action as the region joins a global rebuke of the US manufacturer’s most important plane.

The shares fell as much as 6 per cent in New York. Questions are swirling around the future of the newest version of its 737 family, a cash cow that generates almost a third of the company’s operating profit.

While investigators are still piecing together why an Ethiopian Airlines 737 Max 8 plunged to the ground minutes after take-off Sunday, regulators across the globe opted for caution, even as the US Federal Aviation Administration has said the jet model remains airworthy.