Hong Kong (CNN Business) Hong Kong's main stock index has fallen 5% in two days as the rising number of coronavirus cases creates uncertainty for the global economy. The Chinese yuan also tumbled below an important benchmark.

Hang Seng HSI Theslid 2.6% on Thursday, adding to losses posted Wednesday when investors returned from an extended break over the Lunar New Year and subjected the index to its worst trading session in months.

In total, the index has fallen more than 6% this month.

The yuan tumbled in offshore trading, briefly breaking below the 7 yuan per US dollar mark for the first time this year. That amount is considered to be a psychologically important marker — when the yuan crossed that threshold last year, markets were briefly rattled

The currency was last trading offshore, where it moves more freely than on the mainland, at 6.997 yuan per US dollar.

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