Los Angeles home prices are overvalued by nearly 34 percent and the region ranks among the nation’s largest housing markets at risk for price declines, according to the PMI U.S. Market Risk Index issued Tuesday.

Los Angeles topped the list for overvalued housing prices, with its prices estimated as overvalued by 33.7 percent. L.A. was followed by Sacramento (31.3) and Riverside (30.7).

The index of the quarterly report published by Walnut Creek-based PMI Mortgage Insurance Co. showed that half of the nation’s 50 largest housing markets are overvalued by 10 percent or more. Three are overvalued by 30 percent or more and another 11 are overvalued by 20 percent or more. Of the 14 markets overvalued by 20 percent or more, seven are in California: Los Angeles, Sacramento, Riverside, San Diego, Santa Ana, Oakland and San Jose.

L.A. also came in ninth place out of the markets surveyed in the Risk Index, meaning its prices are at high risk for declines in the next two years.

The median price paid for a home in Los Angeles rose 21.4 to $494,000 in September, from $407,000 a year earlier, La Jolla-based DataQuick Information Systems reported on Tuesday. A total of 10,988 new and resale homes were sold in Los Angeles last month, up 4.6 percent, compared with 10,501 sold in the year-prior period.

The median price paid for a Southern California home was $475,000 last month, up 16.1 percent from a year earlier, DataQuick said.