The summer of open weights

Over the winter of 2025, after the release of Opus 4.5, coding agents grew tremendously and usage exploded. I think this summer is proving itself to be a similar tipping point for open weight models. The compute crunch and pricing As I argued in my margin collapse blogs (part 2 here), we're starting to see some very aggressive moves on pricing. We've seen OpenAI cut the cost of 5.6 Luna - its fast, cheapest tier - by 80%, and now Sol - its flagship - by 20%. Meta is also offering its open model Muse Spark 1.2 for an almost-free price of $0.10/$0.20 per MTok on its contributor tier (where Meta may train on your data - standard pricing is $1.25/$4.25), with currently the cheapest API price for cache reads of $0.002 per MTok on that tier (!). Anthropic hasn't matched this pricing yet, but the FT is leading with a story about the poor uptake of Fable 5 - Anthropic's $10/$50 frontier model, its most expensive tier - (tl;dr: it's too expensive) - headline: "Anthropic's best AI model…