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Silicon Valley’s hottest start-ups have raised $150 billion in funding this year as their financial backers advise them to build “fortress balance sheets” to protect them if the artificial intelligence investment boom fizzles out in 2026.
The largest US private companies have set record raises for 2025, smashing the previous high of $92 billion raised in 2021, PitchBook data showed, with investors rushing to back top AI groups like OpenAI and Anthropic.
Venture capitalists and industry experts said the money will help protect founders from investment downturns as public markets become increasingly concerned about heavy spending on AI infrastructure as well as fueling growth.
“You should make hay while the sun shines,” said Lucas Swisher, a partner at Coatue, which supports OpenAI, Databricks and SpaceX. “2026 may bring something unexpected… Build a strong balance sheet when the market is providing options.”
This year’s fundraising figures have been boosted by some unprecedentedly large deals. These include $41 billion raised by OpenAI led by Japan’s SoftBank, $13 billion raised by Anthropic in September and an investment of more than $14 billion by Meta in data-labeling start-up Scale AI.
Other fast-growing AI companies, including coding agent group Anysphere, search company Perplexity, and AI research start-up Thinking Machines Lab, have also tapped VCs several times this year.
Several investors said they have advised start-ups to build up reserves, while enthusiasm remains about AI’s potential to transform the economy.
“The biggest risk[for start-up founders]is that you don’t raise enough money, the funding environment turns sour and your business could go to zero,” said Ryan Biggs, co-head of venture investing at Franklin Templeton. “Or you can do a little bit of hard work, and if the business takes off, it doesn’t really matter: You’re still exceptionally rich either way.”
On average, start-ups raise new funding every two to three years, according to Carta, a software group that tracks private markets. But recently, the best-performing AI start-ups have been returning to investors in just a few months – even as funding dries up for many smaller start-ups.
“Investors are attracted to those late-stage deals where there is more certainty of who the winner is,” Biggs said. “There are a dozen companies you want to join. Beyond those, it’s a challenging landscape.”
Another driver of the 2025 fundraising boom is that leading AI groups are growing at a much faster rate than previous tech start-ups.
Cursor coding tool maker Anisphere’s valuation has risen from $2.6 billion at the beginning of the year to $27 billion in November. Over the same period, its annual recurring revenue – a metric favored by fast-growing start-ups – grew nearly 20-fold to $1 billion.
Perplexity, the AI search engine trying to challenge Google, has raised money four times in the last year, yet its executives said they don’t need more cash.
Cost pressures have led to more frequent fundraising, especially among groups building “frontier” AI models that require large amounts of computing power and expensive chips.
According to people close to the company, OpenAI’s revenue for 2025 is about $13 billion, but the group is losing billions of dollars every year as it spends on developing its models, products and infrastructure.
High-profile funding rounds are also an opportunity for start-ups to market themselves to potential customers and employees amid an extremely competitive market for AI engineers.
“If I’m a start-up I have to show that my equity is worth more than a pay check,” Swisher says, citing financial technology group Ramp as an example of a start-up that has used its rising valuation as a talent acquisition tool.
Ramp’s valuation has soared from $13 billion to $32 billion through four share sales this year, with the company raising $1 billion in the process.
The flurry of deals means many VC firms have burned through cash faster than anticipated. Many big companies have started the process of raising new funds. These include Thrive Capital, Andreessen Horowitz and Tiger Global, according to public filings and people familiar with the matter.
Groups including Lightspeed Venture Partners and Dragoneer raised new multibillion-dollar funds in December, a sign that the hottest startups will still be able to access more venture capital cash in 2026.
Investors also said founders of the biggest start-ups are beefing up their balance sheets to take advantage of acquisition opportunities, especially if investor sentiment changes next year and smaller rivals struggle to raise new funds.
“Put your seat belt on,” said Jeremy Kranz, founder of VC firm Sentinel Global and former head of technology investing at Singapore’s sovereign wealth fund GIC.
“It’s going to be like a takeover a week once the public markets get busted. These guys will take their $500 billion market cap as a private company and start buying up all over the place.”
