Morning Market Update: March 23, 2010

U.S. stock futures are trading mixed Tuesday ahead of a report on sales of previously owned homes. The National Association of Realtors is expected to say that sales of existing homes fell 1% in February to a seasonally adjusted annual rate of 5 million units. Treasury Secretary Timothy Geithner is scheduled to testify before Congress about government efforts to overhaul mortgage financiers Fannie Mae and Freddie Mac. San Francisco Fed President Janet Yellen is also giving a speech today. In corporate news, KB Home (