China’s box office market may be going from strength to strength, but its stock market just tanked, with the Shanghai Composite Index losing more than 8% of its value in a single day. That’s the worst loss since 2007 and is spreading uncertainty throughout the marketplace. The plummeting market comes even after the Chinese government intervened directly to stabilize shares following weeks of instability.

Several media companies took big hits, with Alibaba Pictures down more than 10% to $2.15 a share; Huayi Bros down 10% to $39.58 a share; Wanda Cinema Line off 6.7%; and Fosun International, who partnered with Jeff Robinov on his upstart Studio 8, down more than 8% to $16.18 a share.

It wasn’t all bad news for media stocks. Beijing Enlight Media (in which Alibaba Group owns a $382 million stake) was up 3.38% to $29.95, and Hunan TV, which has a rich co-financing deal with Lionsgate, was up slightly by 0.14%.

The latest freefall comes after the Chinese government intervened this month to introduce measures it hoped would stop an alarming recent decline that saw the Middle Kingdom’s stock market lose nearly 28% since mid-June amid concerns about slowing growth in the world’s second-largest economy. Some of the measures introduced to stem the slide included prohibiting IPOs and calling on brokerages to invest in the market, as well as the Chinese central bank itself investing an undisclosed amount in China Securities Finance Corp, a state-owned company that makes margin loans to brokers as well as further supporting the CSF through interbank lending, bond issuance, and collateral-backed financing and re-lending.

Today’s tumble appears to be over investor concern that the government’s intervention was unsustainable and short-term. Given the yo-yo pattern of the Chinese stock market — one bull run beginning last October saw a 150% increase in value prior to June’s correction — many commentators are taking today’s movement with a pinch of salt. The underlying fundamentals — of the country’s film industry at least — remain robust with box office growth expected at 30% in 2015.