U.S. AI startups are experiencing unprecedented funding in 2025, with overall startup investment up 75.6% in the first half of the year. AI companies completed 24 mega-rounds of $100+ million by mid-June, with standouts like Anysphere ($900M Series C), Applied Intuition ($600M Series F), and Glean (valued at $7.25B). Total AI funding reached $45.2 billion, averaging $255.4M per deal and outpacing other tech sectors. Investors are prioritizing startups with differentiated technology and clear commercialization paths, particularly in compliance, infrastructure, and developer tools. The sector appears headed for its second-best year ever, though future success depends on these heavily-funded startups delivering real-world returns.