Three major AI startup rounds in May 2026: Parag Agrawal's Parallel Web Systems hits $2B valuation ($100M raised for AI agent search infra), ElevenLabs crosses $500M ARR as BlackRock and NVIDIA join its $11B Series D, and Bret Taylor's Sierra AI raises $950M at $15.8B valuation.
AI chip maker Cerebras Systems raised its Nasdaq IPO price range to $150–$160/share from $115–$125, targeting a fully diluted market value of $48.8 billion. The offering was over 20x oversubscribed ahead of its May 14 trading debut.
ElevenLabs disclosed $500M in ARR and $100M in net new ARR in Q1 2026 alone, as it added institutional backers including BlackRock, NVIDIA, and Deutsche Telekom to its $500M Series D originally announced in February.
Parallel Web Systems, founded by ex-Twitter CEO Parag Agrawal, closed a Sequoia-led $100M Series B at a $2B valuation on April 29. The company provides search and research APIs purpose-built for AI agents, serving over 100,000 developers.
Sierra, co-founded by Bret Taylor, closed a $950M Series E at $15.8B valuation on May 4. The enterprise AI agent company has over 40% of the Fortune 50 as customers and $150M ARR.