Pony AI, the autonomous vehicle startup backed by Toyota, has filed for an IPO in the U.S., lowering its minimum valuation from $8.5 billion to $4 billion. The company operates a modest fleet of 190 robotrucks and over 250 robotaxis across several Chinese cities. Despite increasing revenue, Pony reported significant losses due to high R&D expenses, with over $270 million lost in the past two years. The firm has garnered substantial investments but faces challenges, including regulatory compliance and staffing shortages. The IPO filing revealed extensive risk factors, including potential operational limitations in the U.S.