Nikkei announced that it will lower the weighting of Advantest in the Nikkei 225 index starting October 1, 2026, by applying a cap designed to prevent any single constituent from becoming overly dominant [1]. As of the July 31 closing price, which serves as the reference date for this autumn's periodic review, Advantest accounted for 12.2% of the index, exceeding the 10% threshold that triggers the cap rule introduced in 2022 [1]. To address this, Nikkei will reduce Advantest's price adjustment factor from 7.2 to 6.4 beginning in October [1].
The Nikkei 225 index is calculated using constituent share prices multiplied by a price 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 this year [1].
Further adjustments or removal of the cap will be considered during the semiannual reviews following next spring, indicating that the weighting of Advantest may be revisited depending on future index reviews [1].
No specific market reactions, analyst opinions, or forward-looking statements regarding the impact on Advantest's share price or the broader market were provided in the article [1].
CONCLUSION
Nikkei's decision to reduce Advantest's weighting in the Nikkei 225 aims to maintain balanced representation within the index. The adjustment will take effect in October, with further reviews scheduled for next spring. While the move addresses index concentration, no immediate market reaction or analyst commentary was reported.