CHICAGO—The CBD's office market has steadily grown for such a long time that observers have begun openly wondering when the inevitable downturn will begin. The latest data show that they will have to wait a bit longer.

“A few months ago, it seemed like we were going to have a bit more of a slowdown, but it hasn't happened,” Eric Feinberg, senior vice president, Savills Studley, tells GlobeSt.com. “Leasing activity has remained remarkably consistent during the second half of the year. Area businesses continue to make significant investments in their workforce and workplace.”

The firm just released its report on the fourth quarter, and found that tenants leased about three million square feet, the third consecutive quarter of above-average activity. Deal volume for 2017 totaled 10.6 million square feet, or 15.2% above the long-term historical average. The West Loop – with 4.7 million square feet leased – was the year's hottest submarket. And even though several million square feet of new trophy office space has opened up recently, downtown's overall availability rate was unchanged at 15.5%. The class A availability rate rose by 70 bps to 16.7% during the quarter, but was also unchanged from year-end 2016.