Victorian Premier Daniel Andrews' declaration that Melbourne is set for another lockdown to contain the COVID-19 virus upended the sharemarket, slicing off as much as 1 per cent off from stocks in the last hour of trading.

After spending most of the day higher, the S&P/ASX 200 index slumped from 6067 at 3.15pm to close at 6012.90, a drop of 0.9 per cent. The index fell as low as 6004 during that hour for a loss of 1 per cent.