Bank bid at auctions

If a short sale offer is unsuccessful and the property goes to auction, is the opening bid always equal to the amount owed to the primary mortgage lender (plus legal, taxes etc)? Are there any circumstances under which it would be less? And if so, would the PML always bid up to the amount owed to it?


In my area, lenders opening bid is usually the minimum required by state. In my area, min. bid is 2/3rds of the sheriff’s appraised value.