The Invesco QQQ ETF , which tracks the technology-heavy Nasdaq 100 index , dropped 1.4% in afternoon trading Friday, led lower by the extended pullbacks in the shares of mega-capitalization companies. The QQQs are now down 9.6% month to date, which puts it on track for the biggest monthly percentage decline since it dropped 11.5% in November 2008. Among the three most heavily weighted components of the QQQ, Apple Inc.’s stock has tumbled 16.5% this month, on track for the biggest monthly decline since it shed 18.4% in November 2018; Microsoft Corp. shares have slid 11.6% in September, which puts them in danger of the biggest monthly drop since it tumbled 13.0% in January 2015; and Amazon.com Inc.’s stock has sunk 14.8% in September to date, which puts it on track for the worst monthly performance since it fell 20.2% in October 2018. Meanwhile, the S&P 500 is down 5.2% so far this month, and is headed for the biggest percentage decline since March 2020, when it slumped 12.5%.