After getting off to a rocky start, mainland stocks continued to slide during the day en route to potentially posting their biggest sell-off in more than three years.

All three of the major mainland indexes opened more than 3% down, after U.S. President Donald Trump threatened China with higher tariffs. By mid-afternoon with just a half-hour left in the session, the benchmark Shanghai Composite Index was down 5.8%, and the Shenzhen Component Index was down 7.4%.

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