NEW YORK - New York office building sales are on track to at least match their second-best year on record as investors react to low interest rates and signs that the city's economy held up better than expected after Sept. 11.

The Empire State Building is among $2.8 billion in properties sold this year. That compares with $5.9 billion in all of 2000. The only better year was last year, when the World Trade Center lease sale pushed the total to $10.6 billion.

Rising demand for Manhattan skyscrapers reflects a 9.3 percent vacancy rate at the end of March. That was the second-lowest rate in the nation and below the national average of 13.2 percent. The city added jobs in April for the first time in 11 months.

"Competition for properties is as fierce as it has been in a long time," said Eastdil Realty's Douglas Harmon, who brokered the sale of 450 Park Ave. for $158 million.

As many as 60 buyers, including Germany's Otto Group and the New York State Common Retirement Fund, want to enter or expand their investments in New York real estate, brokers said.

SL Green Realty Corp. made the biggest acquisition this year, paying $483.5 million for the 54-story Times Square tower that houses MTV studios and its parent Viacom Inc., owner of the CBS television network. The price for the building, at 1515 Broadway, was the highest since the lease on the World Trade Center was sold for $3.2 billion in July.

The largest pending deal is for 1290 Avenue of the Americas, a 43-story tower at West 52nd Street. Jamestown, a German real estate syndicator, beat out Equity Office Properties Trust, the largest U.S. office owner, bidding $745 million.