Vietnam shares retreated on Wednesday after hitting an eight-year high in the previous session as investors booked profits.
Activity across much of the region was subdued as most markets were closed for Eid al-Fitr.
Broader Asian share markets turned tail as fears over instability in the European Union returned with a vengeance, sending the pound to three-decade lows and hammering risky assets of all stripes.
MSCI's broadest index of Asia-Pacific shares outside Japan was down 1.2% at 4.30pm.
Oil prices edged lower, extending losses to a third straight session, as fresh bout of concern over Brexit resurfaced amid worries that central banks might not be able to soften this latest blow to global growth.
Investors rushed to safe-haven assets such as sovereign debt and gold, with the yellow metal rallying to its highest in more than two years.
Vietnam's benchmark stock index fell 0.2%, snapping seven sessions of gains. Consumer non-cyclicals and energy stocks led the decline, with Vietnam Dairy Products JSC and Petrovietnam Gas Joint Stock Corp down 0.7% and 1.5%, respectively.
The market will continue to rise for three-four weeks and could reach 670 points, said Nguyen Thanh Lam, an analyst with Vietnam-based Maybank Kim Eng Securities.
Singapore, Malaysia, Indonesia and Philippine stock markets were closed on Wednesday for Eid al-Fitr.