What is the riskiest ETF?

What is the riskiest ETF that an investor should be aware of? Is there a particular sector or asset class that these ETFs typically focus on? Are there any factors that make these ETFs particularly risky, such as high volatility or concentrated exposure to a single asset? How can investors manage the risks associated with investing in these ETFs, and what strategies can they use to mitigate potential losses? It's important to understand the potential risks before investing in any ETF, especially those that are considered to be the riskiest.