The expanding mortgage crisis and credit crunch slammed the Los Angeles housing market in August, with home sales plunging 50 percent from the same month last year and 25 percent from July.

Sales of new and existing homes in Los Angeles County slid to 4,107 units in August, just under half the 8,246 units that sold in August 2006 and well below July’s 5,458 units, according to figures compiled for the Business Journal by Melville, N.Y.-based HomeData Corp.

The pain was widespread, as only a handful of the county’s nearly 300 ZIP codes managed to eke out any sales gains. August’s plunge was even more dramatic considering that the month is traditionally one of the more robust for home sales.

The number of houses that changed owners represents the second-lowest monthly total since HomeData began compiling Los Angeles County data in January 2004. Only the 3,661 homes sold in February – one of the slowest months for sales – was lower.

Similar carnage took place in the condo market with year-over-year sales plummeting 40 percent to 1,168 units. Sales were off 27 percent from July’s 1,601 units.

“These numbers are the first to show the beginning of the impact of the credit crunch that materialized in the last couple months,” said Robert Kleinhenz, deputy chief economist with the California Association of Realtors.

Yet, as has been the case throughout the housing downturn so far, median home prices managed to hold their own. August’s median dropped slightly from its record July level to $579,000, though it was still 5 percent higher than year-earlier levels. Condo prices actually hit a new peak of $460,000, up from July’s $450,000 and from $415,000 a year ago.

Whether the drop in sales is the start of a bleak trend or is merely a statistical aberration tied to the abrupt onset of the credit crunch remains to be seen.

“The size of the drop is unusual and bears close watching in the months ahead,” said Delores Conway, director of the Casden Forecast at the USC Lusk Center for Real Estate.

High-end slowdown

The differing trajectories – home sales down but median prices up – has been due to a strong market for high-end homes with sale prices exceeding $2 million.

But last month, even this market took a hit as borrowers had a much more difficult time obtaining so-called jumbo loans, or those exceeding $417,000.

“Everything was great until about a month ago. Then, on one day – Thursday, Aug. 9 – everything changed as lenders shot up rates on jumbo loans to 9 percent and further tightened guidelines,” said Syd Leibovitch, owner of Beverly Hills-based Rodeo Realty, which mostly deals in homes worth more than $2 million.