Tumbling crude oil futures knocked Asian shares on Monday after producers’ weekend talks failed to agree a plan to curb the global supply glut, while Tokyo stocks slumped as investors assessed the impact of a devastating earthquake in southwestern Japan.

In Qatar, some 18 oil-exporting nations, including OPEC members, failed to agree to stabilize output at January levels until October 2016. A pact fell apart after Saudi Arabia demanded that Iran join in.

Crude oil ended well off the day’s lows, however, with a strike in Kuwait slashing the country’s oil output by more than half. Brent crude futures tumbled about 5 percent to $40.9 while U.S. crude slid about 4.9 percent to $38.42 a barrel.

MSCI’s broadest index of Asia-Pacific shares outside Japan was 0.9 percent lower, pulling away from a five-month intraday high touched on Friday.

A recent rebound in oil and signs that the U.S. economy is slowly improving have helped stocks rally from a steep selloff earlier this year that had pushed the S&P 500 down as much as 10.5 percent.

“Oil prices are going to continue to be very important to the market,” said Mary Ann Hurley, vice president in fixed income trading at D.A. Davidson in Seattle.