The deal is reportedly worth several million US dollars.
The market reversed course to trade lower on Wednesday as selling pressure reappeared toward the last trading minutes of the session.
Cash flow will continue to help the stock market rise to new heights, but it was time for investors to focus on risk management, brokerages said.
Shares gained for six consecutive sessions on Friday thanks to buying focusing on energy stocks and some individual blue-chips, boosting indices despite strong selling of foreign investors.
Shares ended higher on Tuesday on local investors' buying force, while foreign investors continued to flee from the stock market.
Vietnamese shares trimmed losses in late trade on Friday as strong buying force returned to market, helping revive investor appetite after a strain of sell-off earlier the day.