VNX has issued a surveillance regulation to prevent and control profiteering and stock manipulation as the stock market upgrade officially takes effect.

3-phase surveillance framework

The highlight of the new regulation is that surveillance is not limited solely to the trading days of ETF rebalancing but expanded into 3 distinct phases covering the entire lifecycle of an index rebalancing cycle:

• Phase 1 (Early Risk Identification): Begins on the trading day prior to the data cut-off date before FTSE Russell announces information. Regulators will target "potential" stocks that may be added to or removed from the index basket. The data cut-off date is when FTSE Russell collects core metrics such as market capitalization, liquidity, free-float ratio, and foreign room. Early monitoring helps detect cash flows taking early positions based on rumors or insider information.
• Phase 2 (Key Focus Monitoring): Spans from the announcement date to the trading day immediately preceding the effective date of the index. At this stage, surveillance targets narrow down to specific ticker symbols officially selected for addition or deletion.
• Phase 3 (Post-Event Control): Starts on the effective date of the index and extends for 5 subsequent trading days. This process helps regulatory bodies maintain a comprehensive view of capital behavior before, during, and after index adjustments are finalized.

Which stocks are in the crosshairs?

Surveillance applies not only to potential candidates for addition or deletion but also to stocks officially announced by FTSE Russell for inclusion or removal. Notably, HOSE will monitor both individual accounts and groups of accounts if abnormal signs surface.

Under the regulation, review activities will scrutinize three high-risk behaviors:

Capital flows from an account or group of accounts showing signs of controlling, manipulating, or distorting prices and liquidity.

Trading orders intentionally steering the closing price (ATC session) right before the new index basket takes effect.

Front-running trades exploiting insider information.

Upon detecting suspicious transactions, HOSE may require securities firms to provide information and documentation for clarification while simultaneously reporting to the State Securities Commission (SSC) and VNX.

In simple terms, beyond tracking price increases or drops, regulators can trace transaction flows backward whenever unusual patterns emerge.

On September 21, FTSE Russell will officially announce 27 stocks entering the upgraded basket. The addition of these 27 stocks to FTSE index suites could draw in capital from ETFs and index-tracking investment funds. During rebalancing sessions—especially the ATC window—liquidity and price volatility may surge significantly.

According to BSC Securities, the new regulation issued by VNX carries high practical significance by shifting the surveillance approach from "passive reaction" to "proactive prevention and early identification." VNX’s tightened oversight serves as a preparatory step to receive capital flows post-upgrade. Previously, in October 2025, FTSE Russell decided to upgrade Vietnam to Secondary Emerging Market status and reconfirmed this roadmap in its March 2026 review.

To prevent liquidity shocks, capital will not pour into the FTSE Global Equity Index Series (FTSE GEIS) all at once but will be phased across four stages from September 2026 to September 2027. Preliminary semi-annual indicators suggest 27 Vietnamese stocks will join the FTSE GEIS on September 21. Leading large-cap representatives include VCB, VIC, and VHM; mid-caps feature BID, HPG, and VPB, alongside 21 small-cap representatives.