why does it matter so much? Iirc the 30y bond has average tail or average stop-through around 1.5bps, which really is a fraction of daily vol, a third of a standard deviation?In theory, there are all sorts of stats that you could try and interpret, like the proportion of "direct" bids, etc. However, the only thing that really matters is the "tail", i.e. the difference between the auction yield and the yield prevailing just prior.