The Week’s 10 Biggest Funding Rounds: xAI Leads As 2026 Is Off To A Brisk Start

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This is a weekly feature that runs down the week’s top 10 announced funding rounds in the U.S. Check out last year’s biggest funding deal roundup here.

After a big year for venture investment, fueled by the AI boom, 2026 is not showing signs of a slowdown. Quite the contrary, with the first full week of the year bringing us a whopping $20 billion new funding round for Elon Musk’s xAI. We also counted multiple rounds of over $100 million that look minuscule by comparison but are actually very large by traditional venture standards.

1. xAI, $20B, generative AI: Musk’s xAI, the generative AI startup known for its Grok chatbot and the parent company of X (formerly Twitter), said it secured $20 billion in Series E funding from a long list of venture and strategic investors. Founded in 2023, xAI has raised $42.7 billion in reported debt and equity funding to date, per Crunchbase data.

2. Parabilis Medicines, $305M, precision medicines: Cambridge, Massachusetts-based Parabilis Medicines announced it raised $305 million in a Series F financing co-led by RA Capital Management, Fidelity and Janus Henderson Investors. The financing will support continued clinical development of its peptide platform for cancer therapeutics.

3. Soley Therapeutics, $200M, biotech: Soley Therapeutics, developer of a cell stress sensing platform and a pipeline of therapeutics for neurodegenerative disorders and metabolic diseases, closed on $200 million in Series C funding. Surveyor Capital led the financing for the South San Francisco, California-based company.

4. LMArena, $150M, AI: San Francisco-based LMArena, a platform for evaluating AI models and systems, picked up $150 million in fresh funding. Felicis Ventures 1 and UC Investments led the financing, which set a $1.7 billion post-money valuation, nearly triple the value at its seed round in mid-2025.

5. Diagonal Therapeutics, $125M, biotech: Diagonal Therapeutics, a biotech developing disease-modifying clustering antibodies that correct dysregulated signaling in severe genetic diseases, raised $125 million in Series B funding. Sanofi Ventures and Janus Henderson Investors led the financing for the Watertown, Massachusetts-based company. 

6 (tied). Lyte, $107M, physical world AI: Mountain View, California-based Lyte, a startup focused on integrated perception for robotics and AI, emerged from stealth this week and disclosed it has raised $107 million in aggregate funding. The company says its mission is to “give robots the ability to see, understand, and operate safely in the physical world.”

6 (tied). EpiBiologics, $107M, biotech: EpiBiologics, a company working on tissue-selective extracellular protein degradation, says it completed a $107 million Series B financing. Google Ventures and Johnson & Johnson Innovation co-led the round for the San Mateo, California-based company.

8 (tied). Cambium, $100M, advanced materials: El Segundo, California-based Cambium, a startup developing advanced materials for defense, aerospace, and other sectors, secured $100 million in a Series B round led by 8VC 2. 

8 (tied). Rakuten Medical, $100M, cancer therapeutics: Rakuten Medical, a San Diego-based startup focused on photoimmunotherapy for cancer treatment, raised $100 million in Series F financing led by TaiAx. The company is currently enrolling patients into its global Phase 3 trial for recurrent head and neck cancer.

10. Pomelo Care, $92M, virtual care: Pomelo Care, a virtual healthcare provider for women and children, raised $92 million in a Series C funding led by Stripes. The financing set a $1.7 billion valuation for the New York-based company. 

Methodology

We tracked the largest announced rounds in the Crunchbase database that were raised by U.S.-based companies for the period of Jan. 3-9. Although most announced rounds are represented in the database, there could be a small time lag as some rounds are reported late in the week.

Illustration: Dom Guzman