cash, money

After 2024 marked the return of the biotech megaround, 2025 proved it wasn’t just a one-year anomaly.

Last year was characterized by fewer but larger venture capital financings for biotech, with 2025’s top 10 private rounds bringing in nearly $4 billion collectively.

As venture markets rebounded modestly in the second half of 2025, investors focused on later-stage assets in high-value therapeutic areas, signaling a willingness to write checks when the science and market align.

While 2025 lacked the high highs of 2024—see: Xaira Therapeutics' $1 billion fundraise that topped last year’s list—capital flowed more consistently across a group of well-positioned companies.

One of those well-positioned biotechs is obesity-focused Kailera Therapeutics, which followed up its 2024 megaround with another major financing that brought its two-year total to $1 billion. Meanwhile, cardiovascular player Kardigan demonstrated sustained investor appetite with back-to-back raises this year—$300 million in January and $254 million in October.

With analysts predicting continued recovery for 2026, the resurgence of late-stage venture momentum may set the stage not only for additional megarounds but also, hopefully, for a more sustained financing environment across the board.

With that, let’s take a look at 2025’s biggest money raisers in private biotech, starting with Isomorphic Labs and Kailera.

Amount: $600 million

Series: N/A

Month: March

Investors: Thrive Capital, GV and Alphabet

Isomorphic Labs has landed at the top of this year’s list with a $600 million windfall, tying for first with obesity-focused Kailera and signaling the scale of opportunity for artificial intelligence startups in biotech. Of course, it doesn’t hurt that the biotech was also formed by Google’s parent company Alphabet and its science is backed by Nobel Prize-winning innovation.

Isomorphic builds AI models to design potential drugs, such as the Google DeepMind-partnered AlphaFold 3, which is made to predict molecular structures and interactions.

Isomorphic co-founder and CEO Demis Hassabis, Ph.D., along with DeepMind collaborator John Jumper, Ph.D., won the 2024 Nobel Prize in Chemistry for their work on the model.

“This funding will further turbocharge the development of our next-generation AI drug design engine, help us advance our own programs into clinical development, and is a significant step forward towards our mission of one day solving all disease with the help of AI,” Hassabis said in a statement at the time of the raise.

Headquartered in the U.K., Isomorphic was founded in 2021, with the $600 million fundraise marking the drug designer’s first external financing round.

The AI biotech has also secured two votes of confidence from Big Pharma, scoring partnerships with Eli Lilly and Novartis that are worth up to nearly $3 billion collectively. In both collaborations, Isomorphic is tasked with using AlphaFold to discover small molecules for undisclosed targets.

Little has been publicly disclosed about Isomorphic’s pipeline, though the company has said it is working on wholly owned internal programs.