LOS ANGELES—A tracking firm says the median home price in Southern California rose 15 percent last month from April 2009, when prices reached their lows for the housing downturn.

San Diego-based MDA DataQuick reported Tuesday that last month's median of $285,000 was up from $247,000 in April 2009. Last month's median was unchanged from March.

DataQuick also said home sales dropped about 1 percent from April 2009 to more than 20,300, breaking what had been a 21-month stretch during which home sales increased from their year-ago numbers.

The firm speculated that sales may have slacked because buyers were waiting until May to close escrow so they could take advantage of new state tax credits that became effective on the first of the month.