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The 10 Biggest Rounds Of April: Drone Startup Zipline and OpenAI Top List

Updated: Aug 9, 2023

Want to keep track of the largest startup funding deals in 2023 with our new curated list of $100 million-plus venture deals to U.S.-based companies? Check out our new Megadeals Tracker here.

This is a monthly feature that runs down the month’s top 10 funding rounds in the U.S. Check out last month’s top rounds here.

All through last month, U.S.-based startups saw some big rounds, but the largest two came in at the last minute. Both Zipline’s and OpenAI’s rounds broke on the last business day of the month — totaling $630 million in investment. Not bad for one day. Here’s a closer look at the 10 largest funding rounds to U.S.-based startups in April.

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1. Zipline, $330M, drones: Drone delivery startup Zipline raised $330 million in a new funding round, according to Forbes. The new funding pushes the South San Francisco-based startup’s valuation to about $4.2 billion — up 55% from its $2.7 billion valuation two years ago. No lead investor was named, but past investors include big names like Sequoia Capital and Andreessen Horowitz. Founded in 2011, the company has now raised more than $820 million, per Crunchbase data.

2. OpenAI, $300M, artificial intelligence: OpenAI helped kick off the crazy year for AI when it was reported Microsoft had made a massive $10 billion investment into the ChatGPT creator. However, the San Francisco-based AI firm was not done raising cash. Back in January it was reported that the startup was undertaking an offering that could value it at $29 billion. Just on Friday, the other shoe dropped when TechCrunch reported a group of VC firms — including Sequoia Capital and Andreessen Horowitz — have invested more than $300 million at a valuation of $27 billion to $29 billion into the AI innovator. The company has now raised more than $11 billion, per Crunchbase.

3. EquipmentShare, $290M, construction: Construction tech has not been high on the list of investors for several years after the collapse of Katerra. However, that did not stop Columbia, Missouri-based EquipmentShare, which raised a $290 million funding round led by funds affiliated with BDT Capital Partners. The equipment and digital solutions provider serves the construction industry, providing companies a real-time view of job sites and operations, as well as arsenal equipment. EquipmentShare now has more than 150 locations, including additional rental, retail and service locations. Founded in 2014, EquipmentShare has raised nearly $700 million in total equity, per the company.

4. (tied) Orbital Therapeutics, $270M, biotech: Biotech saw some big rounds last month, and none were bigger than Cambridge, Massachusetts-based Orbital Therapeutics’ raise. The startup closed a $270 million Series A led by Arch Venture Partners. Orbital is looking to expand RNA-based medicines including next-generation vaccines, immunomodulation and protein replacement across a variety of diseases. Founded last year, this is the company’s first outside raise, per Crunchbase.

4. (tied) Clear Street, $270M, fintech: Fintech startup Clear Street closed a $270 million investment from Prysm Capital which values it at $2 billion. The raise comes less than a year after the firm raised $165 million at a $1.7 billion valuation. The independent prime broker is building a “modern infrastructure for capital markets.” Its first product is an equity finance platform — processing more than $10 billion in trades every day. Clear Street’s aim is to create a single-source platform to serve all investors, across all asset classes. Founded in 2018, Clear Street has raised more than $600 million, per Crunchbase.

6. Ohmium International, $250M, energy: Green hydrogen is definitely a thing with investors. Green hydrogen firm Ohmium International raised a fresh $250 million in a Series C led by TPG Rise Climate. Ohmium designs and manufactures proton exchange membrane electrolyzer systems, which are needed in the production of hydrogen. The device is used to split water through electrolysis to create hydrogen. The company’s electrolyzer is powered by renewable energy, therefore producing “green hydrogen” with no greenhouse emissions. Ohmium most recently raised a $45 million Series B in April 2022 led by the Fenice Investment Group.

7. CoreWeave, $221M, cloud: Workloads continue to become more specialized and intense, and with that the cloud infrastructure they use needs to keep pace. New Jersey-based CoreWeave has locked up a new $221 million investment to do just that. The specialized cloud provider — which actually started out as an Ethereum mining operation — plans to use the cash to meet the needs of generative AI applications that are now appearing. Flexible cloud infrastructure with better processing will be needed to train large language models for AI, something CoreWeave is looking to provide. With its focus on the AI sector, it may be unsurprising one of the investors in this round was Nvidia, which is leading the charge in designing better AI chips. The round was led by Magnetar Capital, an alternative asset manager. CoreWeave has raised nearly $377 million to date, per Crunchbase.

8. HeartFlow, $215M, health care: The intersection of AI for health diagnostics found a spot on the list this month. Mountain View, California-based heart precision care technology startup HeartFlow raised a $215 million Series F led by Bain Capital Life Sciences. Its noninvasive technology provides a 3D model to analyze the risk of a heart attack. The technology has been used so far by 180,000 patients across 725 hospital systems globally. Founded in 2010, HeartFlow has raised about $793 million, according to Crunchbase data.

9. Astranis, $200M, space: Even as venture continues to slow, VCs keep looking to the stars. San Francisco-based satellite developer Astranis locked up a fresh $200 million at a $1.6 billion valuation, per a Bloomberg report. The new deal was led by Andreessen Horowitz and comes just before the company prepares its first launch of satellites aboard the SpaceX Falcon 9 rocket. Venture dollars have continued to pour into spacetech, even though overall VC investment continues to trend down. Founded in 2015, the company has now raised more than $553 million, per Crunchbase data.

10. Torl BioTherapeutics, $158M, biotech: It seems like new cancer treatments are always able to secure new funding. Los Angeles-based biopharmaceutical company Torl BioTherapeutics closed a $158 million Series B as it looks to develop new biologics for cancer treatment. The round was led by Goldman Sachs Asset Management. The startup — which had not previously announced funding, per Crunchbase — will use the new cash in the development of novel, antibody-based therapeutics to fight cancer.

Big global deals

Several of the biggest deals last month happened overseas.

  • India-based BYJU’S, an edtech startup, raised a $700 million private equity round.

  • Seoul-based autonomous mobility firm 42dot raised a corporate round worth approximately $787 million.

  • Singapore-based online shopping site Lazada Group received $353 million from its parent firm Alibaba, according to reports.

  • China-based SJ Semi, a foundry that implements front-end wafer manufacturing, closed a $340 million Series C.

  • China-based pharmaceutical company Hasten Biomedical completed a $315 million venture round.


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

Illustration: Dom Guzman

Correction: This story has been updated to reflect the investors in the current OpenAI round.


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