List Stacking
List stacking is the practice of overlaying multiple prospecting lists — absentee owners, pre-foreclosures, tax delinquencies, high equity, long tenure — and prioritizing the owners who appear on more than one, on the theory that stacked signals mean stacked motivation.
The logic
Any single list is mostly noise: most absentee owners aren't selling this year, and neither are most long-tenure owners. But an absentee owner who is also tax-delinquent and also high-equity has three independent reasons to take a call. Stacking converts "which list should I buy?" into "which owners appear everywhere?" — a ranking, not a pile. The same budget spent contacting the top of that ranking consistently outperforms spreading it across any single list.
How it's done
Traditionally: export several lists to spreadsheets, dedupe on owner and address, and count overlaps — which is exactly as tedious as it sounds, and stale by the time it's finished. Modern tools compute the overlap live: WhoseTitle's seller-likelihood score is effectively continuous list stacking, weighing tenure windows, distress records, equity, and absentee status per owner, with the underlying signals shown instead of a black-box grade.