Index Rebalancing Takes Effect Today, Driving Divergent Performance Across Major Indices

According to the announcement dated May 29, 2026 by China Securities Index Co., Ltd. (CSI), the SSE 50, STAR 50 and other indices completed their regular constituent rebalancing after market close on June 12. The SSE 50 replaced 5 constituents, while the STAR 50 replaced 4. The adjustment took effect today (June 15), exerting a direct impact on index performance.

Sector Weight Distribution Drives Index Divergence

The STAR 50 carries a heavyweight exposure of 72.06% to Semiconductors & Semiconductor Equipment, supplemented by Technology Hardware & Equipment (12.63%) and Software & Services (4.69%). Technology and growth-oriented sectors collectively account for nearly 90% of the index. The strong performance of technology stocks this morning directly propelled a significant rally in the STAR 50.

The ChiNext Index likewise exhibits a highly concentrated technology profile, with Technology Hardware & Equipment at 42.51% and Capital Goods at 27.53%, combining for over 70%. This sector structure mirrors that of the STAR 50, resulting in highly synchronized performance today with comparable gains.

The CSI 500 and CSI 1000 display relatively balanced sector distributions, though still tilted toward manufacturing and technology. The CSI 500 is heavily weighted toward Materials (19.49%), Technology Hardware & Equipment (17.61%), Capital Goods (14.69%) and Semiconductors (11.80%); the CSI 1000 shows similar weights in Capital Goods (18.50%), Materials (17.69%), Technology Hardware & Equipment (16.40%) and Semiconductors (10.93%). This structure placed both indices in the upper-middle range of today's performance.

The CSI 300 features a more diversified sector mix. Its top five sectors are Technology Hardware & Equipment (19.58%), Capital Goods (13.72%), Banks (10.77%), Semiconductors (9.81%) and Materials (9.20%). The inclusion of substantial financial and traditional industry weights resulted in relatively muted gains.

The SSE 50, as a large-cap blue-chip index, boasts the most balanced sector distribution. Its primary weights are Semiconductors (16.98%), Banks (16.83%), Food & Beverage (11.81%), Materials (10.26%) and Insurance (8.18%). The relative weakness in financial and consumer sectors weighed on the SSE 50, making it the worst-performing index today.

Today's index divergence clearly reflects a market style rotation toward technology and growth. The outperformance of Semiconductors, Technology Hardware, and Capital Goods drove notable gains in the STAR 50 and ChiNext Index. This movement may be attributed to three factors: first, concentrated passive inflows following the effective date of constituent rebalancing; second, strengthened market expectations for a recovery in technology sector fundamentals; and third, increased risk appetite channeling capital into growth stocks.

Risk factors to monitor include: profit-taking pressure following the sharp rally in technology stocks, the fading of rebalancing effects, and whether overall market turnover can be sustained. Should the technology sector fail to attract continued capital inflows, the current index divergence pattern could reverse.