Anthropic, the San Francisco-based maker of the Claude AI model, finalized a lease for 113,000 square feet across multiple floors in South Lake Union.

The deal lands in a market that has posted negative net absorption for 17 consecutive quarters. Seattle's overall office vacancy hit 28% in the first quarter of 2026, according to Kidder Mathews. The central business district sits at 34.7%. Average asking rents have fallen 5.2% year over year to $35.20 per square foot.

Anthropic's 113,000 square feet fills roughly 69% of the north tower at Dexter Yard, a two-building office and life sciences campus developed by BioMed Realty, a Blackstone portfolio company. The LEED Gold-certified building opened in 2022. The campus includes on-site retail tenants including SLU Bru and Cafe Hagen.

If Anthropic fills the space, those businesses and the lunch spots along Dexter and Westlake avenues could see weekday foot traffic they haven't had since 2020. The company requires employees in the office at least 25% of the time and is hiring engineers in Seattle, though the exact local headcount has not been disclosed.

OpenAI and Databricks both expanded their Puget Sound footprints in recent months but chose Bellevue. Anthropic picked South Lake Union, placing itself next door to Amazon's campus.

The proximity tracks with the companies' financial relationship: Amazon committed up to $25 billion in Anthropic in April, and Anthropic simultaneously pledged more than $100 billion in AWS spending over 10 years, according to GeekWire.

In May, Anthropic announced $65 billion in funding at a $965 billion valuation, which GeekWire described as the likely last venture round before an expected IPO later in 2026.

Downtown Seattle Association President Jon Scholes has argued that Seattle's JumpStart payroll tax makes the city less competitive with Bellevue, where no comparable tax exists. "We've lost 30,000 jobs. We're going in the wrong direction," Scholes said in a DSA report on the tax's effects.

Anthropic's decision to expand in Seattle rather than across the lake complicates that argument, at least for AI companies chasing proximity to Amazon's engineering talent.

Dexter Yard sits at the seam between South Lake Union and lower Queen Anne. Separately, the Kidder Mathews Q1 2026 report noted that 3Edgewood LLC acquired the largely vacant building at 222 5th Ave. N in the Queen Anne and Magnolia submarket for $50 million ($248 per square foot). CoStar analyst Elliott Krivenko said in a December 2025 analysis that the steepest rent declines in Seattle had hit the central business district, Belltown, and Queen Anne.

Seattle ranks third among U.S. metro areas for AI industry growth, with AI job postings nearly three times the national average, according to Kidder Mathews.

Sublease availability dropped to 4.97 million square feet in Q1 2026, the lowest share since 2018. New office construction has all but stopped: only 63,527 square feet across three projects remained under construction regionwide at the end of 2025, a 99% drop from 2023's peak.

Anthropic's move-in date has not been announced. A company spokesperson acknowledged the lease but declined further comment.

The south tower at Dexter Yard still has approximately 147,000 square feet available, according to an April 2026 BioMed Realty marketing brochure.