OpenAI cut API prices 50% for two new models launched September 22, 2026, and the discount is measured against a promotional rate rather than list price for the model they replace OpenAI announces GPT-6 Sol and… (community.openai.com)Alignment and Factuality… (openai.com). GPT-6 Sol and GPT-6 Luna extend the GPT-6 family that already includes the flagship Astra, and both were built with what OpenAI calls "similar methods," inheriting Astra's gains in alignment, factuality, coding and computer use Alignment and Factuality… (openai.com). The same day, Microsoft's Azure blog confirmed all three models generally available in Microsoft Foundry, the enterprise platform Microsoft uses to sell OpenAI's models into corporate cloud deployments GPT-6 Luna Deployment and… (azure.microsoft.com).
The number worth sitting with is the baseline. OpenAI states the 50% reduction is "compared with GPT‑5.6 promotional pricing," not GPT-5.6's standard rate OpenAI announces GPT-6 Sol and… (community.openai.com)Alignment and Factuality… (openai.com). A promotional price is temporary by definition; comparing a permanent new price against it produces a bigger discount than comparing it to what most customers were actually paying before the promotion ran. Neither OpenAI source gives the GPT-5.6 standard rate, so the real-terms saving for a buyer who was never on the promo cannot be checked from what OpenAI published.
What Sol and Luna are actually priced to do
Sol is positioned below Astra as what OpenAI calls a cost-efficient high-end model for agentic coding, business workflow automation, computer use, and long-horizon software engineering in real codebases OpenAI GPT-6 Sol Overview and… (openrouter.ai). Luna sits below Sol, aimed at high-volume tasks like summarization and routing where speed and per-call cost matter more than ceiling capability GPT-6 Luna Deployment and… (azure.microsoft.com). That is a three-tier structure — Astra for the hardest problems, Sol for demanding but routine professional work, Luna for volume — replacing what had been closer to a single flagship offering, and OpenAI frames the split explicitly as a strategy of spreading intelligence across a cost curve rather than serving everyone from one model Alignment and Factuality… (openai.com).
OpenAI's benchmark claims for Sol are its own. The company says Sol at its highest reasoning-effort setting outperforms Anthropic's Claude Opus 5 at its own maximum effort on AutomationBench, a test of business workflow automation across applications, while costing 9% of what Opus 5 costs per task Alignment and Factuality… (openai.com). It also reports Sol scoring 56.4% on a separate evaluation called Agents' Last Exam, above the top Opus 5 score there at 60% lower cost per task Alignment and Factuality… (openai.com). Both comparisons come from OpenAI's own release material, run on OpenAI's own benchmark in one case, and there is no independent test of either model in the material reviewed here. Luna's improvements are described only qualitatively, as "substantial," with no equivalent numeric benchmark disclosed for it specifically Alignment and Factuality… (openai.com).
Where the exposure actually sits
The company with the clearest financial exposure to this release is not named in either OpenAI announcement. Microsoft reported Intelligent Cloud revenue of $39.3 billion for the quarter ended June 30, 2026, up 32% year over year, driven by Azure growth of 43% EX-99.1 - SEC.gov. Microsoft Cloud revenue overall reached $59.3 billion, up 27% EX-99.1 - SEC.gov. None of that reporting mentions Sol or Luna, because the quarter closed before the September 22 launch; the two events are contemporaneous with the broader Microsoft-OpenAI commercial relationship, not shown to be caused by it. Deutsche Bank analysts flagged what they called "some concentration risk" in that relationship "especially with the ascent of open-source models," in a note cited alongside Microsoft's July 29 earnings, while still recommending the stock Microsoft (MSFT) Q4 earnings… (cnbc.com). Microsoft's shares had given up 19% year-to-date as of that report Microsoft (MSFT) Q4 earnings… (cnbc.com).