The Week’s 10 Biggest Funding Rounds: SiFive Leads With $400M For Custom Chip Designs As Aviation, Biotech And Defense Startups Also Raise Big

Want to keep track of the largest startup funding deals in 2025 with our curated list of $100 million-plus venture deals to U.S.-based companies? Check out The Crunchbase Megadeals Board.

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

While no billion-dollar rounds led this week’s list, we nonetheless saw a variety of startups in industries ranging from semiconductors to aerospace to biotech raise sizable rounds. The week’s biggest deal was $400 million for SiFive, a semiconductor startup challenging incumbent Arm Holdings with chip designs built on an open rather than proprietary standard.

1. SiFive, $400M, semiconductors: San Mateo, California-based semiconductor startup SiFive raised a $400 million Series G round led by Atreides Management. SiFive makes the blueprints used by companies such as Alphabet to develop their own internal chip designs, on an open standard called RISC-V. CEO Patrick Little told Reuters he expects the raise to be SiFive’s last funding round before an IPO, though didn’t say when an offering would take place.

2. Hermeus, $200M, aviation: Hermeus, an El Segundo, California-based startup developing autonomous military aircraft, raised $200 million in equity in a Khosla Ventures-led round. The company, which is developing what it says will be the fastest unmanned defense aircraft, also raised $150 million in debt as part of the round, which pushes its valuation to $1 billion. Other investors in the deal include Socium Ventures, RTX Ventures, Karman Ventures, Founders Fund, IQT and Cox Enterprises. 

3. Sidewinder Therapeutics, $137M, biotechnology: San Diego-based Sidewinder, a biotech startup developing cancer drugs to target difficult-to-treat tumors, raised a $137 million Series B led by Frazier Life Sciences and Novartis Venture Fund. The company is developing next-generation cancer drugs called antibody-drug conjugates, or ADCs, which are designed to act like “guided missiles” by using engineered antibodies to deliver toxic payloads directly into tumor cells. The company said its new funding will be used to push its lead drug candidates into clinical trials.

4. Aria Networks, $125M, AI infrastructure: Palo Alto, California-based Aria Networks raised $125 million in a Sutter Hill Ventures-led Series A funding round. The company develops an AI-driven networking platform that monitors, analyzes and optimizes data center performance.

5. Starfish Space, $111.7M, aerospace: Starfish Space, a Seattle-based startup developing and manufacturing autonomous space vehicles that perform in-orbit, satellite servicing missions, raised $111.7 million. The Series B round was led by Activate Capital Partners, Point72 Ventures and Shield Capital. Starfish’s spacecraft dock to satellites already in orbit to service and reposition them. They can also remove defunct satellites and debris from space.

6. (tied) Stipple Bio, $100M, biotechnology: Cambridge, Massachusetts-based Stipple Bio raised a $100 million Series A round to advance its precision cancer therapies. The round was led by a16z Bio+Health, Nextech Invest and RA Capital Management. Stipple aims to develop highly targeted cancer treatments that selectively attack cancer cells while minimizing damage to healthy tissue.

6. (tied) Chapter, $100M, health insurance: Generation Investment Management led the $100 million Series E for Chapter, a New York-based startup offering a Medicare navigation platform that provides advisory services for seniors seeking health coverage. Other investors include ​​XYZ Venture Capital, Maverick Ventures and 8VC 1.

8. Modus, $85M, fintech: Modus, a Philadelphia-based startup, raised $85 million in a Lightspeed Venture Partners-led seed and Series A round. The startup describes itself as a tech‑enabled audit platform that acquires CPA firms and equips them with AI‑driven audit tools to deliver higher‑quality audits. Comma Capital and Garry Tan also participated in the deal.

9. Endovascular Engineering, $80M, medical devices: Gilde Healthcare and Norwest led the $80 million Series C for Menlo Park, California-based Endovascular Engineering, also called E2, which has developed a device called Hēlo for the treatment of venous thromboembolism, or VTE. The company secured FDA clearance for Hēlo in December.

10. Life Biosciences, $80M, biotechnology: Boston-based Life Sciences, which aims to develop drugs to promote longevity and find treatments for age-related diseases, says it raised $80 million in Series D funding. The company says it will use the funding to advance human trials of its cellular rejuvenation therapy, called ER-100, which aims to make older, damaged cells act younger again. Investors in the round were not disclosed. The company has previously been backed by Longevitytech.fund, Alpha Wave Ventures, LeFrak, Apple Core Holdings and George Godula.

Methodology

We tracked the largest announced rounds in the Crunchbase database that were raised by U.S.-based companies for the period of April 4-10. 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