viewtopic.php?p=124488#p124488
The reclassification will impact ETFs that track the information technology, consumer discretionary and telecoms sectors, and could potentially see consumer discretionary stocks such as Netflix, Disney, Comcast and Time Warner, and tech stocks such as Apple, Google, and Facebook, move to the newly created communications services sector.
...
The changes will affect ETFs that track information technology stocks such as the iShares S&P 500 Information Technology Sector ETF (IITU LN), which currently has major weights assigned to Apple (16.1%), Google (11.3%) and Facebook (7.8%).
...
The changes will take effect after the close of business on 28 September 2018.
I did sell out of IITU before the change, but held on to some individual stocks like Amazon.
Could this change have been the trigger for the slide we have seen? The timing seems to match.