Anthropic and OpenAI released cheaper models within hours of each other, intensifying competition for business customers increasingly focused on AI costs and returns. Anthropic said Claude Opus 5.5 matches the performance of its flagship Fable 5.1 while costing about 40% less to run than Opus 5, released in July. It called Opus 5.5 its most efficient model and said it would pass the savings to customers through lower prices and higher rate limits. OpenAI launched GPT-6 Sol and GPT-6 Luna as everyday-work versions of GPT-6 Astra, released earlier this month, while cutting API pricing to 50% below a promotion for GPT-5.6, Astra’s predecessor. OpenAI attributed the reductions to improvements in caching and inference, and said it was passing the savings to users. The releases arrived after both companies called for efforts to pace the frontier, meaning to slow development of the most advanced AI models. Anthropic said Opus 5.5 received its most rigorous alignment testing, including outside evaluation, and launched with cybersecurity, biology and frontier-AI-development safeguards previously reserved for Fable 5.1. Analysts cited in the report said the price competition could reduce potential profits, while the more immediate contest may be for everyday business users rather than the most powerful models. Businesses are scrutinizing return on investment, with Caylent calculating cost per task and OpenAI advocating a similar approach in a mid-July 2026 blog post.