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Reebok is offering the vast majority of its Seaport District headquarters for sublease, amid a wave of downsizing by Boston office tenants that is pushing sublease availabilities to record highs.

The athletic apparel manufacturer moved into the Innovation and Design Building in 2017, and put its sprawling Canton campus on the market. The firm is offering at least 175,000 square feet in its space in the Innovation and Design Building, according to quarterly brokerage reports.

Reebok joined a wave of suburban office tenants relocating to Boston in the past decade amid competition for employees who prefer to work in an urban setting.  It leased 220,000 square feet at the Innovation and Design Building and touted perks for its 700 employees such as a mile-long track and 30 daily fitness classes at a 2-story gym designed by Gensler.

But the company’s parent, Adidas, sold it for $2.5 billion in 2021 to Authentic Brands, which has a strategy of acquiring struggling brands.

Reebok spokespeople did not respond to messages about the sublease attempt.

Tech, advertising, media and information companies are responsible for a large portion of the new subleases in Boston, according to market reports by local brokerages.

Wayfair, Drift, Cengage, GrubHub and LogMeIn put nearly 1 million square feet of sublease space on the market in the third quarter, according to Newmark’s Boston office report.

Back Bay and the Seaport District have the highest sublease availability levels of 3.6 and 3 percent of their office inventory, respectively, according to Avison Young’s quarterly report.

Total sublease availabilities in Boston hit an all-time high of 3.6 million square feet, according to Avison Young, representing 4.6 percent of the market’s inventory. That exceeds the 4.5 percent mark during the Great Recession.