Heavyweights knock ASX below 6200; Afterpay and Macquarie rise

Summary

• An uninspired ASX slipped into the red on Friday, with biotech CSL and miners BHP and Rio Tinto weighing
• The local bourse is lagging most major Asian markets, with the exception of Korea's KOSPI. US futures were up by between 0.2% and 0.3% at about 2pm AEDT 
• The Aussie dollar fell to a two-week low US70.56 cents overnight. It was worth US70.82 cents by 2pm AEDT
• Rio Tinto's third-quarter iron ore shipments fell 5% due to planned maintenance in the Pilbara. The company left its full-year guidance unchanged, even though the works will continue over the next three months