(Bloomberg) -- The cost for short-term options on China-linked ETFs traded in the US rose to fresh highs Monday as shares extended a rally ahead of onshore markets reopening Tuesday after a week-long holiday.

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Implied volatility for one-month options on $2.3 billion Xtrackers Harvest CSI 300 China A-Shares ETF (ASHR) jumped to a record high, while the same measure for $9.3 billion iShares China Large-Cap ETF (FXI) reached the highest level since 2020 and $8.36 billion KraneShares CSI China Internet ETF (KWEB) hit a two-year high.

Call options on the US-traded ETFs are getting bid up along with shares in Hong Kong. The iShares China Large-Cap ETF one-month calls reached the highest premium over bearish contracts since 2008, as did options on the Hang Seng Index, as investors flood back in to Chinese equities after the government announced a broad package of stimulus measures.

Some of the bigger trades appeared to be rolling profitable positions higher as the ETFs have rallied anywhere from 30% to more than 50% in the past two weeks. Trading volume Monday was boosted by a 400,000-contract trade in FXI, where a trader shifted one side of a March-expiry call spread opened Sept. 30 to a higher strike, spending $19 million for the chance to make a larger profit if the rally extends.

There were some signs of investors buying protection against the rally fading, with put options trading that would protect against about a 30% drop in ASHR.

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