A mutual mistake of fact in a separation agreement very likely provides a basis for reforming the title to the co-op apartment a couple owned together even though they never actually changed the form of ownership indicated on their stock certificate, a divided appeals panel in Manhattan ruled yesterday.

In remanding the matter for trial, Justice David B. Saxe (See Profile) wrote that evidence in the record leaves “little doubt” the divorcing parties intended to eliminate each other’s survivorship interests.