Major Deals Mark O.C. as Hot Property : Investment: Many of the largest deals in land and office buildings in the Southland have been recorded in Orange County. Japanese firms figure prominently in the transactions.

When big real estate investors haul out their wallets in Southern California these days, they’re as likely to be buying property in Orange County as in Los Angeles or San Diego.

Nine of the 25 biggest transactions in Southern California through 1989 and into this year were in Orange County. Of the 10 largest deals in the region, half were in Orange County, according to a survey by San Diego’s Comps Inc. for The Times.

In 1988, 11 of the 25 largest deals were in Orange County.

Half of the major pacts in Orange County in 1989 and early 1990 involved land rather than buildings. But there were also some big sales of recently built Orange County office towers as the once-suburban county rapidly urbanizes. Those sales came despite bargain-basement office rents in Orange County--and throughout Southern California--because of a glut of office space. In fact, the weak market has scared off many U.S. institutional investors such as pension funds, said Joseph A. Leon, a commercial real estate broker at Coldwell Banker’s Newport Beach office.

“The market’s very soft,” he said.

So the two biggest Orange County office deals were done by Japanese investors, who have spread out from the big markets of Los Angeles and New York to secondary markets including Orange County.

Those transactions include the third-largest in Southern California in the last year and a half: The $82-million sale of Los Angeles-based Transamerica Insurance Co.’s interest in two buildings at Koll Center Irvine Southwest near John Wayne Airport to a group of Japanese companies calling themselves World Trade Center Building. The deal, which closed in October, included the 11-story Transamerica Building and the five-story Marine National Bank building, totaling 345,000 square feet. Transamerica sold because it wanted out of the anemic office market.

The Koll Co., the big Newport Beach developer that built the office towers in partnership with Transamerica, retains an unspecified amount of ownership in the buildings.

The fourth-largest deal in Southern California was the $80-million sale of The Atrium in Irvine near John Wayne Airport, two 10-story towers linked by a glass atrium. Although the buildings’ 336,000 square feet were nearly all leased, the rates were so low that the owners were said to be having a tough time making a profit. The building was sold in late 1989 by local developers French & McKenna to Hyogo Real Estate USA Inc., a Japanese investment firm.

But the Japanese may not be able to maintain such a strong presence in the local market, said Leon of Coldwell Banker. Interest rates are rising in Japan, and many of the big players already hold well-stocked real estate portfolios.

Instead, Leon said, investors from other Pacific Rim nations may take up the slack as some, including Taiwan and Korea, loosen foreign investment restrictions.

Big apartment deals are slow ing, the Comps survey shows. Real estate brokers say owners want unrealistically high prices given their inability to raise rents much.

“Until recently, investors were paying these wild prices,” said Julie M. Hagberg of Apartment Properties, a Santa Ana investor and broker. “Now the banks and the thrifts are a little more conservative and a little more experienced, and you just can’t get financing to buy most apartments.”

And there were as many deals for large, expensive tracts of land around Southern California as there were for office buildings, according to the survey.

The two largest land transactions in the region in the last 1 1/2 years were in Orange County: The $75-million purchase of 3,510 acres near San Clemente called Talega Valley, and the $71-million purchase of 224 acres around the Los Alamitos Race Course in Cypress.

In San Clemente, Florida developer Arvida Corp. plans to build 5,000 homes on the land it bought from Talega Valley Partnership.

In Cypress, buyer Cypress Development Partnership plans to build offices and a hotel, and to refurbish the race track and a nearby golf course on the property it bought from Hollywood Park Realty Enterprises Inc.