From debut to peak, S3’s borrow cost and squeeze signals clarify CATL’s A/H dynamics.

Global Leader, Dual Listings: Contemporary Amperex Technology (CATL) is the world’s largest EV battery maker, controlling ~38% of global market share. It trades as A-shares (300750 CH) in Shenzhen and, since May 2025, as H-shares (3750 HK) in Hong Kong.

Debut Premium: On May 20, CATL’s H-shares opened at HK$306.2 versus ~HK285.2 (currency-converted) for A-shares, a modest 7.4% premium. Early trading looked typical for a dual listing in price discovery.

Spread Blowout: By July 28, H-shares closed at HK$462.0 versus currency-adjusted A-shares at ~HK$319.1, a 44.8% premium. From the May 20 debut through that peak, H-shares gained 51% compared to just 12% for A-shares. Notably, S3’s Short Squeeze Score reached 100 on June 27—when H-shares were HK$300—flagging stress ahead of the price surge.

Short Interest & Divergence: As of Sept 10, S3 data shows short interest of 23.5M shares, representing 34% of free float and valued at approximately HK$10B (US$1.29B). Since the July peak, H-shares declined by 7.8% while A-shares gained 8.3%, narrowing the spread but leaving a significant premium intact.

Borrow Costs & Entrenched Premium: By Sept 10, H-shares traded at HK$428.8 versus A-shares at ~HK$345.7, a ~24% premium. S3 data shows borrow costs at 17–19% annualized, putting some timing pressure on arbitrageurs—though easing from the late-August peak near 23%.

Short interest in CATL’s H-shares continues to edge higher, adding to already crowded positioning. Borrow costs remain elevated in the high teens, while the A/H premium holds near 24%—still wide enough to tempt arbitrageurs but increasingly sensitive to financing costs and timing. In the risk factors of its listing disclosures, CATL cautioned that H-shares could be highly volatile and prone to moves disconnected from fundamentals, and the spread has borne that out since debut. After narrowing steadily from July’s peak, the premium has begun to widen again over the past week, with shorts adding incrementally.

Talk to S3 to see how our short interest, borrow cost, and squeeze analytics can sharpen your positioning.

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The information herein (some of which has been obtained from third party sources without verification) is believed by S3 Partners, LLC (“S3 Partners”) to be reliable and accurate. Neither S3 Partners nor any of its affiliates makes any representation as to the accuracy or completeness of the information herein or accepts liability arising from its use. Prior to making any decisions based on the information herein, you should determine, without reliance upon S3 Partners, the economic risks, and merits, as well as the legal, tax, accounting, and investment consequences, of such decisions.