Who knows how deep the current downturn in home sales will go? The crystal ball is cloudy for everyone. But one thing is clear: many Giants are rushing into high-density infill development — including high-rise condo buildings — just as housing demand is faltering, and that's a dangerous move.

Masters Of The Universe (Giants 6-31), which includes majority of publicly-held home builders, have a big lead in closing high-rise condos, but projects under construction indicate Supernovas (Giants 1-5) will soon find traction in this market segment.

High-rise condos have much in common with rental apartments, including an easy propensity for over-building. When there's demand that everyone can see, too many builders may rush to meet it, and two years later there's a surge of inventory. A lot can change during the 18 months to two years it takes to build a high-rise.

Unlike a suburban subdivision, where a builder can slow down — or even stop construction — a condo tower is an all-or-nothing proposition: "Once you get past the foundation, and start putting bricks in the air, you're going the whole way," admits Toll Brothers chairman Bob Toll, "whether people are canceling contracts or not. You can't stop a high-rise."

The demographics of housing demand indicate an upswing in urban projects for at least the next ten years, risk or no risk.