Business: But Holding High on Flats

While the market for houses is slumping, sales of condominiums and cooperative apartments are holding up better. They account for only 2.3% of all U.S. housing, but in recent years they have become the hottest properties in residential real estate, and supertight money seems unlikely to put more than a temporary brake on demand.

The attraction of co-ops and condos is simple: they offer the tax and investment advantages of home ownership, but usually for less money. Their appeal is strong among retired people squeezed by rising rents, young married couples and middle-income suburbanites...