Key Highlights

• Promotion Winners See Inflows: Nextpower and Southern Copper benefited from promotion into growth or large-cap benchmarks.

• Removal Losers Face Forced Selling: Circle Internet Group and Firefly Aerospace faced pressure after removal from respective Russell benchmarks.

• Mechanical Flows Independent of Fundamentals: Passive index flows can drive significant short-term price action regardless of underlying company performance.

The Russell index reconstitution effective June 29-30, 2026 created clear divides between winners and losers across multiple sectors, demonstrating how mechanical index-driven flows can significantly impact individual stock performance independent of fundamental developments.

Nextpower and Southern Copper (NYSE: SCCO) saw inflows from promotion into growth or large-cap benchmarks, with Nextpower graduating from the small-cap Russell 2000 to the Russell 1000 and Southern Copper added to the Russell 1000 Growth and Russell Top 200 Growth indexes.

ACM Research (NASDAQ: ACMR) also gained from reclassification into Russell growth indexes, including the Russell 2000 Growth and Russell 2500 Growth benchmarks, attracting potential new growth-focused institutional investor interest.

Conversely, Circle Internet Group (NYSE: CRCL) and Firefly Aerospace (NASDAQ: FLY) faced forced selling pressure after removal from Russell growth and value benchmarks respectively, as passive funds tracking those indexes were required to sell their holdings.

This pattern demonstrates how passive index flows can drive significant short-term price action independent of fundamentals, creating both opportunities and risks for investors who fail to account for these mechanical, non-fundamental drivers of stock price movement.

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