Chai Discovery

Joshua Meier and Jack Dent met in computer science classes at Harvard UniversityHarvard UniversityHarvard University is a private research university in Massachusetts, established by the Massachusetts Bay Colony legislature in 1636 and named in 1639 for early benefactor John Harvard. Its principal campuses are in Cambridge and the Allston and Longwood neighborhoods of Boston. It includes Harvard College, graduate and professional schools, and the Radcliffe Institute for Advanced Study. Two governing boards share oversight. Alan M. Garber was president as of October 2026, and the endowment stood at $56.9 billion at the end of fiscal 2025.Open the full entry. Meier worked on OpenAI’s research and engineering team in 2018; after he left, OpenAI CEO Sam AltmanSam AltmanSam Altman is an entrepreneur and investor, and the co-founder and chief executive officer of OpenAI. He previously served as president of Y Combinator and founded the location-based social service Loopt. He also helped found Tools for Humanity and Merge Labs, has invested in energy and life sciences ventures, and has driven public discussion of AI governance, employment, and wealth distribution.Open the full entry contacted Dent, then an engineer at Stripe, to ask whether Meier would be open to collaborating on a proteomics startup. Meier felt the technology was not yet ready and instead joined Facebook, where he helped develop ESM1, the first transformer protein language model, before spending three years at the AI biotech company Absci.⁠[1][1][1][1][1][1][1]

In 2024, Meier and Dent got back in touch with Altman and founded Chai Discovery together with Matthew McPartlon and Jacques Boitreaud, initially working out of OpenAI’s offices in San Francisco’s Mission neighborhood. The company is headquartered in San Francisco, California; its team comes from organizations such as OpenAI, Meta FAIR, Stripe and Google X, and most of its members have served as Head of AI at drug discovery companies.⁠[1][1][2][3][3]

On September 9, 2024, Chai Discovery announced a seed round of about $30 million led by Thrive Capital, OpenAI and Dimension Capital, with participation from Conviction, Neo, Lachy Groom and Amplify; angel investors included Greg Brockman and Fred Ehrsam, among others.⁠[4][4]

The same day, the company released Chai-1, a multimodal foundation model for molecular structure prediction that can jointly predict proteins, small molecules, DNA, RNA, covalent modifications and more. Chai-1 achieved a 77% success rate on the PoseBusters benchmark (versus 76% for AlphaFold3) and can also run in single-sequence mode without multiple sequence alignments. The company made the model available free of charge through a web interface, including for commercial uses such as drug discovery, and released the model weights and inference code under the Apache 2.0 license.⁠[3][3][3][3][3]

In June 2025, the UK government announced up to £8 million in funding from its Sovereign AI Unit for the OpenBind consortium, which is building a large open dataset of drug–protein interactions, and invited Chai Discovery and other companies to an investment roundtable at 10 Downing Street. Joshua Meier said the company was keen to contribute its open structure prediction technology to the effort.⁠[5][5][5][5]

On June 30, 2025, the company released the Chai-2 series of models for zero-shot de novo antibody design. In experiments against 52 protein targets with no known antibody binders, testing at most 20 designs per target, it achieved a 16% binding rate in a single experimental round and at least one successful binder for 50% of the targets; in miniprotein binder design, its wet-lab hit rate was 68%. The company described this as about a 100-fold improvement over previous computational methods that could shorten hit discovery from months or years to two weeks. Chai-2 was opened to selected academic and industry partners under the company’s Responsible Deployment policy.⁠[6][6][6][6][6][6][6]

On August 6, 2025, Chai Discovery announced a $70 million Series A led by Menlo Ventures, including its Anthology FundAnthology FundAnthology Fund is a $100 million AI investment initiative launched by Menlo Ventures and Anthropic in 2024 and financed by Menlo. It backs early-stage AI companies with capital, Anthropic resources and company-building support, with scope for follow-on investments.Open the full entry run jointly with AnthropicAnthropicAnthropic is an artificial intelligence research and product company founded in 2021 that develops the Claude models, assistant, and tools such as Claude Code, and operates as a public benefit corporation. Dario Amodei and Daniela Amodei are its co-founders, and its research covers model safety, interpretability, and steerability.Open the full entry; new investors included Yosemite, DST GlobalDST GlobalDST Global is a technology investment firm founded by Yuri Milner in 2009 that focuses on growth-stage investments in internet companies worldwide; it has invested in companies including Facebook, Twitter, Alibaba, JD.com, Airbnb and Spotify, and in 2026 led the US$400 million Series B round of the AI visual content company Higgsfield.Open the full entry Partners, SV AngelSV AngelSV Angel is a San Francisco venture capital firm cofounded in 2009 by angel investor Ron Conway and former Google executive David Lee. It typically writes small follow-on checks in seed rounds and has invested in companies such as Airbnb, Pinterest, and Dropbox; in 2018 it said it would no longer raise new funds from outside investors, and from 2022 it set up growth funds.Open the full entry, Avenir and DCVCDCVCDCVC (Data Collective) is an American deep tech venture capital firm founded in 2010 by Matt Ocko and Zachary Bogue, with offices in Palo Alto and San Francisco, California. It invests in companies that use computing and AI to solve real-world problems in fields such as energy, climate, biomedicine, defense, space, and industry; as of October 2026 it had more than $4 billion in assets under management across 13 funds.Open the full entry, and existing investors such as Thrive Capital, OpenAI and Dimension also invested. Former Pfizer Chief Scientific Officer Mikael Dolsten joined the board of directors.⁠[7][7][7][7]

In November 2025, the company reported that Chai-2 could design full-length monoclonal antibodies (mAbs) rather than only single-domain or scFv fragments. Of 88 IgG designs against 28 antigens, 86% had at most one flagged issue across four developability criteria; cryo-EM analysis of five designed antibody–antigen complexes showed each antibody binding where the model intended, with sub-angstrom accuracy even in the CDR loops.⁠[8][8][8][8][8][8]

The company also used Chai-2 to design antibodies against six G protein-coupled receptors (GPCRs), which are difficult to tackle with screening methods, obtaining binders to each after testing 10 to 73 designs per target and agonists for two of the GPCRs directly from the model; against an MHC complex presenting a KRAS G12V peptide, it obtained two specific binders that did not bind G12D or wild-type KRAS peptides.⁠[8][8][8][8]

On December 15, 2025, Chai Discovery announced a $130 million Series B co-led by Oak HC/FTOak HC/FTOak HC/FT is a venture capital and growth equity firm headquartered in Stamford, Connecticut, that focuses on healthcare and financial technology. It was spun out in 2014 by the healthcare and fintech team of the venture firm Oak Investment Partners and has invested in companies including VillageMD, Aspire Health, and CareBridge.Open the full entry and General CatalystGeneral CatalystGeneral Catalyst (GC) is an investment firm founded in 2000 and headquartered in San Francisco, United States, created by Joel Cutler, David Fialkow and Bill Fitzgerald, that backs companies from the seed stage through growth.Open the full entry at a valuation of $1.3 billion; existing investors including Thrive Capital, OpenAI, Dimension and Menlo Ventures participated, and Emerson CollectiveEmerson CollectiveEmerson Collective is an investment and philanthropic organization founded by Laurene Powell Jobs and headquartered in Palo Alto, California. Structured as a limited liability company, it supports businesses and nonprofits through venture investments, grants and collaborative programs in education, economic mobility, immigration, the environment, health and media.Open the full entry and Glade Brook joined as new investors. Annie LamontAnnie LamontAnnie Lamont is an American venture capitalist and the co-founder and managing partner of Oak HC/FT, a healthcare and financial technology investment firm. She previously led healthcare and fintech investing at Oak Investment Partners for many years and has invested in companies including athenahealth, One Medical, VillageMD, and CareBridge.Open the full entry of Oak HC/FT and Hemant Taneja of General Catalyst joined the board.⁠[9][10][9][9]

On January 9, 2026, the company announced a collaboration with Eli Lilly: Lilly will use Chai’s AI platform to design biologic therapeutics for multiple targets, and Chai will train a purpose-built model on Lilly’s large-scale proprietary data for Lilly’s exclusive use. Lilly had previously evaluated a set of Chai’s model designs. At that point, the company had raised nearly $230 million in total.⁠[11][10][10][10][10]

On June 4, 2026, the company announced a license agreement with Pfizer under which Pfizer will use Chai’s AI platform in drug discovery, with early access to the previously undisclosed Chai-3 model and a custom model built with Pfizer’s proprietary data and tailored to its workflows. The company said Chai-3 doubles its predecessor’s success rate in AI antibody design and improves therapeutic binding, multispecific molecules and binding to hard-to-drug targets.⁠[11][11][12][12][12][12]

On June 18, 2026, Chai Discovery reached an agreement with Lilly’s TuneLab platform, its second with Lilly, allowing biotech companies in early biologics discovery to evaluate Chai’s miniprotein design suite.⁠[11]

On July 13, 2026, the company announced a collaboration with Novartis, which will gain access to its latest models, including Chai-3, for therapeutic antibody discovery across multiple targets; the two companies had more than a year of prior technical engagement. Financial terms were not disclosed.⁠[2][2][2]

On July 14, 2026, Chai Discovery announced a $400 million Series C at a valuation of $3.8 billion, led by Index Ventures with Kleiner Perkins, Sequoia CapitalSequoia CapitalSequoia Capital is a venture capital firm founded by Don Valentine in 1972, investing from the seed stage through the growth stage. Its historical investments include Apple, Cisco, Google, YouTube, Airbnb, and Stripe; in 2021 it introduced the Sequoia Capital Fund structure, which can continue to hold public securities, and in 2023 its regional businesses became independent brands and partnerships.Open the full entry and Dimension; new investors included Bain Capital Ventures, Battery VenturesBattery VenturesBattery Ventures is a global venture capital and private equity firm focused on technology companies, investing from seed-stage startups through growth investments and buyouts.Open the full entry and Baillie Gifford, and existing investors such as Thrive Capital, OpenAI, Oak HC/FT, Menlo Ventures and General Catalyst invested again. Dimension founder Zavain Dar said it was the largest check Dimension had ever written. The company said the funds would expand the compute, data and research behind its models and accelerate product development.⁠[13][13][13][13][13][14]

On July 15, 2026, the company announced a collaboration with the immunology company argenx, which will gain early access to Chai’s AI platform for de novo antibody discovery against multiple therapeutic targets.⁠[15][15][15]

On August 20, 2026, the company announced a collaboration with Bristol Myers Squibb, which will use Chai’s molecular folding and design models to discover antibody candidates across its portfolio.⁠[16][16][16]

On October 9, 2026, the company announced a collaboration with GSK following a technology evaluation. In the evaluation, Chai’s models generated designs for GSK’s targets without target-specific training, and GSK’s internal wet-lab testing found binders to every target tested; GSK will now gain access to Chai’s protein folding and design models for use across its pipeline. GSK was the sixth pharmaceutical partner Chai had announced in nine months.⁠[17][17][17][17][18]

Chai Discovery: Official website: https://www.chaidiscovery.com/ (opens in a new window).⁠[19]