I *think* I recall reading about this a month or two ago. In the past, Realty Trac numbers were derived by listing the number of notices filed for NOD/NOT, and they were listing all NOT filings as bank owned. Someone called BS and they changed their reporting to list “unique addresses”. When they changed their reporting criteria, that number of NOD/NOT fell due to properties that had had several filings (1st & 2nd loans). These would be reconciled to the single address. I think that they also started tracking Bank Owned by the title transfer, not not the NOT.

That would account for the pretty big jump in numbers realtytrac has been reporting.