Toll Brothers Inc., Lennar Corp. and KB Home are among three big homebuilders facing the default of two joint-venture developments in Las Vegas, Nv. called Inspirada and Kyle Canyon Gateway. The two projects, which also involve some smaller homebuilders and Focus Property Group in Las Vegas, have reportedly received default notices on $765 million in debt. One of the smaller homebuilders, Kimball Hill Homes, is reportedly considering whether it should file for Chapter 11 protection. The default on the Vegas properties raises questions about the exposure of such homebuilders. They often set up joint ventures to diversify the risk involved with big projects but the homebuilders typically don't disclose the risk involved with such projects to investors.