MSCI August 2026 APAC index review performance Report Interpretation

Overview

This is a short APAC event-performance monitor for the MSCI August 2026 index review. It identifies the largest post-announcement moves among securities affected by review-related changes and compares their returns with their contribution to the relevant index-review flows.

Core views

J.P. Morgan’s monitor covers the MSCI August 2026 index review across APAC, grouping affected securities into additions, deletions, other buys and other sells. The review was announced at the close of 12 August 2026 and is scheduled to take effect at the close of 31 August 2026. The report’s purpose is descriptive: to identify the largest share-price movers after the announcement and to chart buy-sell spread movement around the event. Kioxia Holdings (285A JT) was the standout name in the report’s rankings. It was ranked first by absolute contribution, at 2.17%, and recorded a 24.03% return since announcement. In the one-day performance table, it again led with a 15.08% return and a 1.43% contribution. The report therefore places Kioxia at the center of the observed APAC review-related price action, rather than presenting a fundamental company thesis or rating. Other since-announcement movers cited in the performance tables included Nanya Technology at 10.01%, Kingboard Holdings at 9.13%, LG Innotek at 8.44%, Samsung Electronics at 7.60%, Ememory Technology at 7.52%, and Yang Ming Marine Transport at 7.18%. Negative moves included Winbond Electronics at -8.98%, Caliway Biopharma at -6.03%, International Games System at -5.19%, Phison Electronics at -4.43%, and Seibu Holdings at -3.91%. The one-day ranking also showed strong positive returns for Puya Semiconductor A at 13.40%, Yangtze Optical Fibre H at 12.14%, H World Group ADR at 11.29%, King Slide Works at 10.67%, Jentech Precision Industrial at 10.66%, Largan Precision at 10.65%, Unimicron Technology at 10.48%, and Ccoop Group A at 10.02%. On the negative side, Ememory Technology declined 9.43%, while MPI Corp and Gigabyte Technology each declined 9.39%. These rankings separate absolute return from contribution, so a large price move does not necessarily correspond to the largest aggregate impact in the monitor.

Analysis framework

The report uses an event-performance approach: it identifies securities associated with MSCI review change categories, then ranks the top 20 APAC movers by post-announcement return and by contribution. It compares both cumulative performance since the 12 August announcement and one-day performance, with data sourced from MSCI, Bloomberg Finance L.P., and J.P. Morgan.

Methodology notes

• Event-Driven and Behavioral FinanceEvent-driven analysis

  Index-review event performance monitoring

  The report examines how securities linked to MSCI review changes performed after the announcement, using returns and contribution rankings to show where event-related price action was concentrated.

Asset mapping & comparison

Structured mapping from thesis to named assets (strengths, weaknesses, peers, risks).

• Kioxia Holdings (285A JT)

  Leading MSCI August 2026 review performance mover in the APAC monitor.

  Strengths

  24.03% return since announcement and 15.08% one-day return.

  Comparison

  Ranked first by absolute contribution at 2.17%, ahead of the other listed APAC movers.

• Nanya Technology (2408 TT)

  APAC review-related addition in the since-announcement mover table.

  Strengths

  10.01% return since announcement.

  Comparison

  Below Kioxia Holdings’ 24.03% since-announcement return.

• Winbond Electronics (2344 TT)

  APAC review-related deletion in the since-announcement mover table.

  Weaknesses

  -8.98% return since announcement.

  Comparison

  Among the largest negative movers cited in the monitor.

Key data

• MSCI August 2026 review announcementClose of 12 August 2026The event date used for the since-announcement performance monitor.
• MSCI August 2026 review effective dateClose of 31 August 2026Scheduled implementation date.
• Kioxia Holdings since-announcement return24.03%Highest highlighted return in the since-announcement table.
• Kioxia Holdings one-day return15.08%Highest one-day return in the monitor.
• Kioxia Holdings contribution2.17%Ranked first by absolute contribution in the report.

Impact & implications

The report indicates that MSCI review-related flows were accompanied by sharply divergent APAC share-price reactions. Its contribution and return tables help distinguish securities with the largest price changes from those with the greatest aggregate effect in the monitor.

What to watch

• Implementation of the MSCI August 2026 review at the close of 31 August.
• Further changes in the buy-sell spread and in post-announcement returns among affected APAC securities.