It's no secret that the housing market has suffered huge setbacks over the past 24 months. Americans have already lost $13 trillion in net worth and the bloodbath doesn't appear to be over.

Real estate markets that went on a building binge during the expansion phase are projected to lose as much as 25% in housing value in 2009. It's the talk of the town, and most of us are sick of hearing about it.

But what does it mean for the apartment market? At one point it seemed a corpse could apply for a home loan and get approved in a matter of days. That put enormous pressure on apartment communities as they battled for anyone with a pulse to fill vacant units.

A few years later and well into the housing boom, apartment rents increased dramatically as home prices escalated out of control. Now fast forward to the housing bust. At first, rental rates surged further and concessions were nearly nonexistent. Foreclosures soared in 2007 and 2008 and consumers were tossed back into the renter pool. Vacancy fell and cash flow increased.

Today, however, the multifamily sector faces new challenges, like the "shadow" market, which consists of homes and condos that compete with apartments for renters. Apartment communities are again offering free rent and other bonuses to attract potential residents.

Net operating income (NOI) is decreasing and fearful investors are panicking. During a Web seminar on Feb. 24, managing director Linwood C. Thompson of the National Multi Housing Group of Marcus & Millichap said vacancy rates are, "going to go up on average about 100 basis points (bps) across the entire portfolio. That's a significant move."

If you liked this article you might like

DuPont vs. Peltz and 4 More Corporate Conflicts Headed for Showdowns

Ready to Invest in REITs? Deals Expected to Surge This Year

Will This Downgrade Hurt Essex Property Trust (ESS) Today?

BRE Properties Inc. (BRE): Today's Featured Real Estate Laggard

Water-Logged And Getting Wetter: BRE Properties (BRE)