NEW YORK CITY—While leasing activity in Manhattan was stable and office availability flat during the month of August, a number of factors contributed to a rise in the average asking rent to a seven-year high at $69.35-per-square-foot.

In a report released today by Newmark Grubb Knight Frank, the brokerage firm reports that office availability in August was flat month-over-month at 11.2%, but finished higher than the 10.7% rate posted a year ago as a result of 1 World Trade Center and 7 Bryant Park reaching completion in the past 12 months.

NGKF attributes the rise in asking rents to some landlords re-pricing their assets and the additional of several new space availabilities in prime office buildings. A total of 2.4 million square feet of office space was leased during the month of August, fueled primarily by mid-sized tenant activity in Midtown and Midtown South.

The largest transactions were closed at Brookfield Place properties. The Associated Press announced it will relocate operations from 450 W. 33rd St. to 200 Liberty St. The deal involves the AP downsizing its footprint by 40% to 172,000 square feet. In another deal at Brookfield Place, financial services firm KCG Holdings committed to move its headquarters from Jersey City, NJ to 300 Vesey St., where it will occupy 168,873 square feet.

Tech and creative firms accounted for 49% of total leasing volume in August, including eight of the 10 largest deals. Midtown South attracted much of this activity, including two notable expansions in the Park Avenue South submarket, NGKF officials state. Houghton Mifflin Harcourt signed its second lease at 3 Park Ave. this year, adding 45,269 square feet for a total footprint of 78,713 square feet; and William Morris Endeavor expanded at 11 Madison Ave., adding 44,000 square feet bringing its total occupancy at the property to 114,425 square feet.

The financial sector remained highly active in Midtown, accounting for 30% of the total square footage leased in August. Top-of-the-market space continued to draw mid-sized investment firms and hedge funds, particularly in the Park Avenue and Upper Fifth/Plaza submarkets. Medley Capital Corporation leased 22,000 square feet at 280 Park Ave., while TRB Advisors renewed its 20,483-square-foot offices at 767 Fifth Ave.

Availability remained flat in August in Midtown at 11.7%, while asking rents reached $81.07/SF, a 6% increase from this time last year and the highest since late 2008.

Large blocks of space hitting the market in the Penn Station submarket nudged Midtown South availability up to 9.3% in August from 9.1% in July. Midtown South asking rents continued to climb, reaching a historical high of $62.47-per-square-foot this month. Asking rents have increased 9% over the past year, driven by heightened demand for space and tightening availability, the report states.

After a subdued first half of 2015, Downtown leasing activity rebounded in August and is now on pace to be the strongest quarter of leasing since the third quarter of 2014, NGKF states. Availability fell to 12.9% in August from 13.2% in July, but finished up from 12.1% last year due to the delivery of 1 World Trade Center and the addition of several blocks of shadow space to the market.