By the end of Monday session, GAS shares of state-owned oil and gas corporation PetroVietnam Gas JSC rose 2.38 percent, its biggest increase since May.

BSR shares of Binh Son Refinery JSC, one of Vietnam’s two oil refineries, jumped a record 5.7 percent, while PLX shares of major state-owned oil and gas distribution giant Petrolimex rose 1.3 percent.

Similarly, other stocks belonging to the government’s oil and gas group PetroVietnam (PVN) also recorded increases. PVS shares of PV Technical Services Corporation, PVD of PV Drilling, and PVB of PV Coating rose 3.6 percent, 3.4 percent and 2.5 percent respectively, with transaction volumes roughly doubling over the last session.

Vietnam’s benchmark VN-Index closed with an increase of 2.64 points (0.27 percent) to 989.86 points by the end of Monday. 323 stocks gained and 287 stocks lost during this session.

The VN30-Index for Vietnam’s 30 biggest market cap companies also registered a modest 0.39 percent rise, led by blue-chips such as VNM of dairy giant Vinamilk, up 1.2 percent; MSN of food conglomerate Masan Group, up 1.7 percent; and VJC of budget carrier Vietjet Air, up 1.7 percent.

The HNX-Index, a smaller exchange accounting for roughly 10 percent of market cap across all trading floors, fell 0.02 percent while the UPCoM, a market for unlisted public companies, fell 0.23 percent.

Brent crude futures, the international benchmark, rose by as much as 19.5 percent to $71.95 per barrel in the first minutes of trading on Monday after unmanned aerial vehicles struck Saudi Arabia’s biggest crude-processing facility in Abqaiq and the kingdom’s second-biggest oil field in Khurais on Saturday.

State energy producer Saudi Aramco lost about 5.7m barrels per day of output, equivalent to 5 percent of global supply on the markets. The company has not given a timeline for when output can be restored, Reuters reported.