In natural language and daily life, it has become prevalent there is a class of entities which do not follow the abstract concrete distinction. Many people refer to abstractions that exist in time. (for example: there is a company that you can invest in) SEP mentions the criteria of abstract objects as those which do not exist in time or space (wikipedia also defines it this way, as well as abstract objects not having physical referents)
Entities such as the United States, the Company of Apple, a hurricane, the afterlife, or even reality appear abstract because they do not exist entirely in space, but certainly they exist in time, or not? Are "abstractions" different from abstract objects? Is there a third realm for entities that are immaterial, but exist in space and time? Are they still abstract?