Is it possible to rank/rate ETFs from the standpoint of their riskiness?
I am aware of Morningstar's star-based ratings, but based on my limited research they seem to take into account only returns and volatility of these returns. Basically, an ETF based on US Treasuries (iShares 7-10 Year Treasury Bond ETF) can be rated lower than an ETF of US Stocks (iShares Core S&P Total US Stock Mkt ETF). This is somewhat questionable, in my opinion (but apparently some regulators are fine with it).
I would appreciate any color on the subject. Thank you.