"Shrugging off repeated signs that conditions have noticeably weakened, vendors are pushing stock levels to near-record levels in both the auction and private sale markets."
I don't think they are 'shrugging off' anything. I'd say they are trying to capitise on the current over-inflated prices before it's too late.
OR
Maybe they take the HC bulls advice and wait a few weeks for 15% YOY growth to kick back in.
