A drop in home orders at KB Home sent the home-builder's shares lower and raised concerns about the spring selling season.

KB Home's results partly reflected strategic decisions that turned out badly for the builder, but data released Friday by the Commerce Department showed that sales of all new U.S. homes were weaker than expected in February.

The data highlighted a major difference between the market for new homes and the market for existing homes."The new-home market is off way more from its peak than the existing-home market is, and the big difference is investors," said John Burns, a consultant based in Irvine, Calif., who tracks the national housing market.