One of the most heavily traded ETFs in the world is the Invesco QQQ Trust (QQQ). The Nasdaq 100 tracking ETF trades over 50 million shares on average per day and nearly 3 million options on top of that. Last week, an institution or fund purchased a whopping 65,000 puts in QQQ that expire in September. The trader spent about $115 million on premiums for what could be a hedge against a drop in the tech sector.