The benchmark VN Index on the HCM Stock Exchange dropped by 0.5 per cent to close at 570.41 points, adding to a 4.2 per cent decrease since last Wednesday.
The HNX Index on the Ha Noi Stock Exchange was down 0.4 per cent to end at 80.26 points, down 2.2 per cent during the last four days.
The insurance sector index yesterday dropped 2.9 per cent, led by Bao Viet Holdings (BVH), which fell 3.7 per cent.
"Bao Viet declined yesterday after foreign investors sold this stock strongly due to fears that the Vietnamese dong will weaken against other currencies, especially the US dollar", said Nguyen Xuan Binh, Deputy Head of Bao Viet Securities Corporation's Market Analysis.
The dong could weaken by as much as 4 per cent next year following an interest rate hike made by the US central bank later this month, he said.
The recent rise of the selling price for the US dollar by local banks also discouraged foreign investors from buying local shares, which reduced the flow of foreign investment into the Vietnamese stock market, Binh said.
On Monday, local banks kept their selling prices between Vietnamese dong and the US dollar around VND22,530 and VND22,545 – almost equal to the limit level set by the State Bank of Viet Nam, which is VND22,547.
In addition, the Japan-based media firm Nikkei Incorporate yesterday announced that Viet Nam's Purchasing Managers' Index (PMI) fell from 50.1 in October to 49.4 in November, indicating Vietnamese firms were going through a small slowdown in manufacturing.
The slowdown for manufacturing and processing sector came after new orders fell slightly for a third month due to lower market demand while production remained unchanged in November, Nikkei said.
The reduction of input costs following lower commodity prices such as oil and steel also made the output prices lower for local companies. Meanwhile, they had more inventory due to lower purchasing power, Nikkei added.
Those findings mean local producers will have worse performances on the stock market, Bao Viet Securities Corporation (BVSC) wrote in a report.
Following Nikkei's statement, local producers such as Vinamilk (VNM) fell 1.6 per cent, autopart producer TMT Automobile Joint Stock Company (TMT) was down 1 per cent, Garmex Saigon Joint Stock Company (GMC) dropped 1.3 per cent.
Both local bourses traded more than 152.7 million shares, worth VND2.23 trillion ($99.4 million) – a decrease of 15.5 per cent from Monday.
