Secondly, a lack of symmetry may not be conducive to the clarity of communication, especially when the arguments for lowering policy rates need to be explained. However, the Eurosystem clarified a) that the use of the word "increase" excludes deflation and b) that the lack of an explicit lower bound acknowledges the existence of an unknown and possibly time-varying measurement bias in the HICP.
Instead, they simply accepted investment-grade ratings as a substitute for their own risk analysis. Market participants may also have assumed that these vehicles had sufficient funding liquidity, or would receive bank liquidity support if funding became an issue. In observing these cases of insufficient due diligence, I am reminded of the old adage "Trust but verify."