Downtown properties continued to change hands in the third quarter even as vacancies stagnated and average asking rates for Class-A space rose only slightly.

“This past quarter was very slow,” said commercial real estate broker Scot McBeath. “This may be a temporary situation caused by deals taking longer to do as the market becomes less favorable for all but larger tenants.”

Average asking rates for Class-A space was $2.64 per square foot, compared with $2.61 in the previous three months and $2.63 for the like period a year earlier, according to Grubb & Ellis Co. Class-B asking rates rose 2 cents to $1.98, the highest recorded since 2001. Meanwhile, the vacancy rate of 15.6 percent was slightly under the 15.9 percent for the April-June period.

“Investors will pay premiums for office buildings just to get a foothold in the market,” said Chris Runyen, senior managing director of Charles Dunn Co. Inc. “We’ve continued to see more investment activity at higher prices, but we haven’t had any significant tenants enter or leave the downtown market.”

Trizec Properties Inc. purchased the 52-story, 1-million-square-foot Figueroa at Wilshire office building from Houston-based Hines and German investment fund Deutsche Immobilien Fonds AG for $356.7 million, or $343 per square foot. The building, at 601 S. Figueroa St., is Trizec’s third acquisition in the downtown market.

Tishman Speyer Properties LP is purchasing 400 S. Hope St. from the pension fund of law firm O’Melveny & Myers LLP for $245 million, or $349 per square foot. The building, known as Mellon Bank Center, is Tishman’s sole downtown property. O’Melveny & Myers leased back 350,000 square feet for 10 years at undisclosed rates, the largest lease deal recorded in the quarter.

In a smaller acquisition, LaeRoc Partners bought the Gerry Building from MJW Investments for $14.3 million. The historic 115,000-square-foot building at 910 S. Los Angeles St. was renovated in 2001.

Steve Bay, executive vice president for CB Richard Ellis Group Inc., suspects that buyers are considering replacement costs and comparing Westside rates when making decisions.

“With the increased cost of construction, replacement costs are much higher,” he said. “Investors are thinking, ‘If it would cost $400 per square foot to build, why not buy?’ So they think they’re coming out ahead.”

Getting increased rates will be tough, however, especially with little interest from outside the market. Some brokers hope for another tech boom fueled by Microsoft Corp., which relocated downtown from 2700 W. Colorado Blvd. in Santa Monica.

The software giant took 37,000 square feet at Wells Fargo Tower. Terms were not reported. The deal brings the property’s occupancy to 86 percent.

“There’s a distinct possibility that the Microsoft deal will turn a lot of heads,” said John Eichler, senior director with Cushman & Wakefield Inc. “It could cause smaller software and high technology companies to consider coming to downtown.”

Peer 1 Network, a broadband and server co-location company, already took advantage of downtown’s Internet pipe by establishing a 2,000-square-foot office at 600 W. Seventh Street for 10 years at $5.5 million.

The bulk of the third-quarter leases came from tenants already in the market.

The Los Angeles Unified School District leased 117,054 square feet at 1055 W. Seventh St. in a 10-year, $25-million transaction. LAUSD will move much of its operation to Wells Fargo Tower next summer, vacating 255,000 square feet at 355 S. Grand Ave. Other employees will be relocated to the district-owned Beaudry Building.

In other deals, FTI Consulting Inc. restructured its lease for 36,000 square feet at 633 W. Fifth St. in a 10-year, $5.5 million deal.

While the 15.6 percent downtown vacancy rate is the lowest in years, it’s still the fourth-highest in Los Angeles County. Only three markets are higher, all in the South Bay: El Segundo/Beach Cities (18.7 percent), 190th Street Corridor (24 percent) and LAX/Century Boulevard (32.8 percent).

Downtown saw positive absorption for the fifth quarter in a row, closing the period with 108,798 square feet of positive net absorption.

“Absorption is strong, but there is less demand than the numbers show,” said Runyen. That’s because often space that’s available for sublease isn’t included in the figures. Many brokers in the market estimate that actual vacancy is probably around 20 percent.

Brokers maintain that two large mixed-use projects at the north and south ends of town will start to attract more office tenants. On Bunker Hill, the Grand Ave. project is a $1.8-billion mixed-use property adjacent to the Disney Concert Hall developed by Related Cos. and designed by architect Frank Gehry. On the other end of downtown, Anschutz Entertainment Group is building L.A. Live across from the Staples Center. The lodging and entertainment complex will span 4 million square feet.

“This will give us a first glimpse of what the new downtown will look like,” Runyen said.