The lender said in a recent report that the figure, which far exceeds those of Malaysia and Indonesia, was due to the increase in new investors and recovery of the economy.
In March, the number of new trading accounts hit a record 113,900 , taking the total to over 3.02 million.
The economic recovery is underpinned by strong FDI flows, improvements in the manufacturing segment and increased consumption, the report said.
The benchmark VN-Index has risen 12.9 percent in the year-to-date compared to 4.2 percent for Asia ex-Japan.
The index has repeatedly scaled new peaks this year after surpassing the psychological barrier of 1,204 points first reached in 2018.
HSBC expected the market to continue to rise in the absence of alternative asset classes and bank deposit rates in decline.
Though foreign investors have been pulling out of the stock market, HSBC said they would not be able to ignore Vietnam for much longer since it has proved to be one of the most resilient growth economies and 24 out of the 30 blue chips have still not reached the foreign cap.
Besides, despite rising to record levels, the VN-Index remains 5 percent lower than its five-year average level with a price-to-earnings ratio of 15.1.