It's a real estate rule of thumb: during economic recessions, co-op apartments are generally more popular than luxury condominium listings. The ostensible reasoning is that co-ops -- which demand more money down and involve what is often a painfully rigorous screening process -- are less volatile than condos. That is the rule of thumb, anyway. But a new report in The Wall Street Journal thumbs its nose at that particular rule of thumb by pointing out that, during the recent/ongoing recession, the market for NYC condos has been notably stronger than that for Manhattan co-ops. While this was especially true for luxury condo listings at the higher end of the condo price spectrum, it's more or less true for all Manhattan condominium listings. The big question, of course, is why.