News: BAL Bellamy's Australia Expects Additional One-Off Inventory Write-Down In H1, page-188

ASX down move (in the morning) began almost at the same time when the news of the arrest of Huawei's CFO (in Canada for extradition to US) was published as breaking news in main media outlets.

The arrest was on Dec 1st (around the time of G20). It appears it didn't have an impact back then. A bit odd for main media outlets to report it a few days later and tie it US-China trade tensions and stock market.

But anyway I guess it gave ASX a reason to fall.

Again IMO ASX down move was needed to maintain ASX correlation with US. The rest is an after-event explanation of the move