Market wrap: Stocks tumble, led by GAS. The VN-Index fell for the fourth time this week, declining 1% on Friday. The index was down 1% for the week and down 2% for the month of May. Following a drop in global oil prices, GAS (-3.5%) was the leading contributor to the day’s loss. PLX (-2.6%) also fell. Banks weighed heavily on the index as VCB (-0.7%), CTG (-1.7%), TCB (-1.5%) and BID (-0.9%) were among the top 10 laggards.