A股兆易創新午後觸及跌停，成交額達310億；港股兆易創新(03986.HK)跌超14%。

CSI 300 index was down as much as 2% intraday.

A $1.8 trillion rally that lifted Asian chipmakers into the top tier of global stocks is reversing, prompting investors to cut exposure and flagging concentration risk in the MSCI Emerging Markets index. Fidelity International and BlackRock said they question the sustainability of rallies in names including SK Hynix and Samsung Electronics. Over the past six months the three largest chip firms’ combined market cap has nearly doubled and now represents about 29% of the MSCI EM index, larger than most single-country weights. Fidelity multi-asset PM Caroline Shaw warned index concentration and a sharp rise in leveraged bets on Korean chip names that amplify price swings are warning signs. The trio’s weight is roughly three times the total weight of all India stocks in the index, and SK Hynix alone exceeds the combined weight of Brazil and South Africa. BlackRock Investment Institute global chief investment strategist Wei Li said volatility in large chip and memory names has prompted the firm to take profits at this stage and trim its EM overweight versus the benchmark.