The California-based startup Fireworks AI has secured a US$250 million Series C funding round at a valuation of approximately US$4 billion. Led by major investors including Lightspeed Venture Partners, Index Ventures and Sequoia Capital, the company supplies AI-inference-platform infrastructure to enterprise clients. The fresh capital will support global expansion, product R&D and scaling of operations. The round highlights continuing appetite for AI-infrastructure plays even amid broader VC caution and reflects a selective focus on enterprise-software and data-centre growth.