Nikkei announced that it will lower the weighting of Advantest in the Nikkei 225 index starting October 1, 2026, as part of its periodic review process [1]. This adjustment is being made because Advantest's weight reached 12.2% of the index, based on the July 31 closing price, surpassing the 10% threshold that triggers the cap rule introduced in 2022 [1]. The cap is intended to prevent any single constituent from becoming overly dominant within the index [1].
To implement this change, Nikkei will reduce Advantest's price adjustment factor from 7.2 to 6.4 beginning in October 2026 [1]. The Nikkei 225 index is calculated using constituent share prices multiplied by this adjustment factor, which reflects past capital changes [1].
The capping rule was first applied in autumn 2024 to Fast Retailing and was used again in spring 2025. Advantest was also subject to the rule during the index's spring review earlier this year [1]. Further adjustments or the potential removal of the cap will be considered during the semiannual reviews following next spring [1].
No specific market reactions, analyst opinions, or forward-looking statements beyond the review schedule were mentioned in the article [1].
CONCLUSION
Nikkei's decision to lower Advantest's weight in the Nikkei 225 reflects the enforcement of its cap rule to maintain balanced index composition. The adjustment will take effect in October 2026, with further reviews planned for the future. No immediate market reaction or analyst commentary was provided.