Large format industrial leasing has roared back, and with it a narrative that big box warehouses are the market's bright spot. That story is true but incomplete. Not all big box buildings are performing equally, and the differences between size segments are stark. This report examines three tiers:

— Mid-size (200–500k square feet)
— Large (500–750k sf)
— Mega (750k sf and above)

The mega segment is tightening fast, with falling vacancy, stronger lease economics and growing rent momentum. Meanwhile, tenants continue to hold the upper hand in the mid-size segment.

Vacancy is falling at the top, rising at the bottom

The numbers behind the divergence are striking. Mega segment vacancy stood at 7.3% in Q1 2026, down 100 basis points year over year and the tightest of the three tiers. The large segment followed a similar trajectory, declining approximately 90 basis points over the same period to 10.1%. The mid-size segment tells the opposite story: at 10.9% and still trending higher, it reflects a supply overhang with little sign of near-term resolution.