Stock price when the opinion was issued
Basically the NASDAQ 100. Acts as a benchmark for a lot of people like himself. Extremely liquid. Trade, rather than invest. Top was around $550, and he thinks it will probably take out those highs before the end of the year.
Based on the look of the chart, he'd write calls against it with a strike of around $530-540. This way, you collect some premiums. If you don't want to get taken out, just keep rolling the strike price up.
Likes that strategy a lot, makes a lot of sense. It would keep the tech exposure, but de-emphasize the weight of the market cap.
In the US, there are some ETFs in the Innovator line. Gives you upside exposure, but contains buffers that protect on the downside for you.