What is happening with AI startup office leasing in 2026? AI startup office leasing in 2026 is the most concentrated burst of demand the Manhattan office market has seen since the dot-com era, with JLL Q1 2026 data showing AI firms leased 415,000 square feet in a single quarter, the average AI lease size doubled to 34,500 square feet, and AI cloud company Nscale Global Holdings set a new Manhattan rent record at 320 dollars per square foot at One Vanderbilt. For CRE investors and landlords, the surge is fundamentally reshaping office market fundamentals in the largest US gateway market. For a comprehensive view of how AI is changing the broader CRE landscape, see our complete guide to AI tools for commercial real estate investors.
Key Takeaways
- AI firms leased 415,000 square feet in Manhattan in Q1 2026 alone, equal to roughly half of all AI leasing volume in 2025 (845,000 SF) per JLL research.
- Average AI tenant lease size doubled from 16,600 SF in 2025 to 34,500 SF in Q1 2026, with 55 percent of AI leasing committed to future growth space.
- Nscale Global Holdings signed at One Vanderbilt for 320 dollars per square foot, setting a new Manhattan rent record.
- Anthropic, the maker of Claude, is reportedly in the market for 250,000 to 450,000 SF in Manhattan, a 12 to 45 times expansion from its current 10,000 to 20,000 SF footprint.
- Manhattan office vacancy fell to 13.5 percent by early April 2026 and trophy availability dropped 22 percent year over year, allowing landlords to raise asking rents above 83 dollars per square foot.
The Q1 2026 JLL Data: 415,000 SF in 90 Days
JLL Q1 2026 Manhattan office leasing research showed total leasing velocity near 9 million square feet, almost matching the record Q1 2025 total of 9.1 million square feet. Within that total, AI firms accounted for 415,000 square feet of new leasing in a single quarter, half of all 2025 AI leasing volume. The Q1 2026 pace, if maintained, would deliver more than 1.65 million square feet of AI leasing for the full year.
The average AI tenant lease size also doubled year over year, from 16,600 SF in 2025 to 34,500 SF in Q1 2026, with 55 percent of that leasing committed to future growth space. AI firms are taking 60 to 100 percent more space than current headcount needs, a pattern reminiscent of the late-1990s tech boom. Many landlords are insisting on 7 to 10 year terms and underwriting AI tenants on balance sheets, capital raised, and revenue projections rather than traditional credit metrics.
The Nscale One Vanderbilt Rent Record
The headline data point in JLL's Q1 2026 research is Nscale Global Holdings, an AI cloud platform, signing at One Vanderbilt for 320 dollars per square foot, setting a new Manhattan office rent record. The previous record was held by a financial services tenant at a similar Park Avenue trophy tower. AI tenants are now setting the high-water mark on rents, not financial services, a structural shift in the Manhattan office hierarchy.
For trophy tower landlords (SL Green, Vornado, RXR, Tishman Speyer, Brookfield), this is the most material data point in the cycle. Trophy availability dropped 22 percent year over year and asking rents rose more than 1 dollar per SF this quarter to 83.51 dollars on average, per JLL. CRE investors holding trophy-tower exposure are seeing a rent recovery that very few underwriters projected in 2023.
Anthropic's 250,000 to 450,000 SF Manhattan Hunt
Per JLL research and multiple market sources, Anthropic, the maker of Claude, is reportedly in the market for 250,000 to 450,000 square feet in Manhattan, a 12 to 45 times expansion from its current 10,000 to 20,000 SF footprint in the city. A lease in the middle of that range would place Anthropic among the top 10 AI tenants in Manhattan by footprint and would set a new record for AI lease size in a single transaction.
This kind of expansion is enabled by Anthropic's recently disclosed 900 billion dollar reported valuation and the 50 billion dollar funding round in market, which gives the company the balance sheet to commit to long-dated trophy tower leases. CRE investors looking for hands-on AI implementation support to understand which tenants drive sustainable demand can reach out to Avi Hacker, J.D. at The AI Consulting Network.
The Harvey AI and Clay Deals: Sub-Sector AI Expansion
The Q1 2026 leasing surge is not limited to the largest AI labs. Two notable sub-sector AI deals closed in Q1 2026.
Harvey AI, the legal AI firm valued at 11 billion dollars after a 200 million dollar funding round earlier in 2026, doubled its footprint at SL Green's One Madison Avenue to 185,000 square feet. Harvey's customer base grew to more than 100,000 lawyers in early 2026, justifying the expansion. The Anthropic Claude for Legal launch (May 12, 2026) and the Thomson Reuters CoCounsel partnership are now driving demand for legal-AI specialist office space.
Clay, the Brooklyn-based AI sales firm valued at 3.1 billion dollars, signed a 10-year lease for 163,000 square feet at 11 Madison Avenue, bringing the building to 100 percent occupancy. AI-driven sales workflow tools are now a credible enterprise category, validated by Salesforce and HubSpot acquisitions and partnerships.
The Dot-Com Comparison Landlords Are Watching
JLL Vice Chairman Evan Margolin noted in the Q1 2026 research that the AI leasing surge is reminiscent of the dot-com era, and we can all remember how that ended. Manhattan office leasing volumes hit 31.5 million square feet in 2000, the year the dot-com bubble peaked. The 2026 leasing surge is closer to that pace than any quarter since.
The structural difference between 2000 and 2026 is the underwriting. Landlords in 2000 leased to startups on growth projections and venture capital balance sheets without strong revenue. Landlords in 2026 are underwriting AI tenants on revenue, contracted backlog, and disclosed funding rounds, with many requiring 7 to 10 year terms, sizable security deposits, and corporate guarantees from parent entities. Some landlords are also offering shorter leases (3 to 5 years) at higher rents to balance the AI-startup concentration risk.
What This Means for Office Owners and Investors
For office owners with trophy Manhattan exposure (One Vanderbilt class), AI demand is the largest tailwind in the cycle. Asking rents are rising, vacancy is compressing, and the tenant mix is shifting from traditional financial services to AI tenants willing to pay record rents for the right product.
For office owners with Class A non-trophy exposure (lower Midtown, Midtown South), AI overflow demand is starting to fill space that was vacant in 2023 to 2024. Clay's 163,000 SF deal at 11 Madison Avenue is the marker case.
For office owners with Class B and C exposure in non-trophy submarkets, the AI surge is unlikely to drive direct demand. The flight to quality continues. The bifurcation between trophy-tower NOI growth and tail-of-market vacancy is now sharper than at any point in the cycle.
For office REITs, the rent compression unwind that started in late 2025 is now meaningfully visible in Q1 2026 disclosure. SL Green, Vornado, and Empire State Realty Trust have all reported leasing velocity increases attributed in part to AI tenants in their Q1 2026 earnings. For investors evaluating the AI infrastructure stack alongside office, see our complete 2026 software guide for AI tools in real estate.
The Concentration Risk Lenders Are Watching
For mortgage lenders underwriting trophy tower refinances in 2026, the AI tenant concentration is now a material disclosure item. A building with 30 to 40 percent of NOI from AI tenants, none of which have multi-decade operating history, is a different credit risk than the same building with 30 to 40 percent of NOI from investment-grade financial services tenants.
According to the May 2026 Cushman & Wakefield AI impact on CRE report, projected AI-driven CRE demand could reach 330 million square feet by 2035. The bull case is realized through office, data center, lab, and industrial demand. The bear case, which lenders are also pricing, is concentration risk if AI funding cools.
If you are ready to transform your CRE underwriting process to model AI tenant credit risk, The AI Consulting Network specializes in exactly this kind of analysis.
Frequently Asked Questions
Q: How much office space did AI firms lease in Manhattan in Q1 2026?
A: AI firms leased 415,000 square feet in Manhattan in Q1 2026, equal to roughly half of all AI leasing volume in 2025 (845,000 SF). The average AI lease size doubled from 16,600 SF to 34,500 SF, with 55 percent of leasing committed to future growth space, per JLL research.
Q: What is the new Manhattan office rent record set by an AI tenant?
A: Nscale Global Holdings, an AI cloud platform, signed at One Vanderbilt for 320 dollars per square foot, setting a new Manhattan office rent record per JLL Q1 2026 data.
Q: How much space is Anthropic looking to lease in Manhattan?
A: Anthropic is reportedly in the market for 250,000 to 450,000 square feet in Manhattan per JLL research and market sources, a 12 to 45 times expansion from its current 10,000 to 20,000 SF footprint. The expansion is enabled by the company's reported 900 billion dollar valuation and the 50 billion dollar funding round in market.
Q: Should office investors worry about a dot-com-style AI office bust?
A: Some landlords and lenders are concerned about AI tenant concentration risk. The structural difference from 2000 is the underwriting: 2026 landlords are requiring 7 to 10 year terms, sizable deposits, corporate guarantees, and revenue or funding evidence rather than purely projections. Concentration in single submarkets and single tenant types still warrants caution.
Q: Which Manhattan office submarkets are benefiting most from AI demand?
A: Trophy-tower Midtown product (One Vanderbilt, Park Avenue) is leading the rent gains. Class A Midtown South (One Madison Avenue, 11 Madison Avenue) is seeing overflow AI demand. Class B and C product in non-trophy submarkets has not benefited materially, with the flight-to-quality bifurcation widening through Q1 2026.