Anthropic disclosed that its AI system Claude authored more than 80% of code merged into production systems as of May 2026, according to a June 4, 2026 report from the Anthropic Institute. The increase followed the February 2025 rollout of an in-house coding agent, after which Claude's contribution rose from low single-digit percentages. The company recently submitted a confidential IPO registration and has positioned its brand around AI safety.
Claude Authored 80% of Merged Code as of May 2026
Before the in-house coding agent launched in February 2025, Claude wrote only low single-digit percentages of merged code, the report states. That share exceeded 80% as of May 2026. Anthropic's typical engineer merged eight times as much code per day in the second quarter of 2026 as in 2024, with human engineers directing and reviewing while Claude performs the writing.
The Anthropic Institute paired internal data with public benchmarks in the disclosure. The company stated that Claude-written code was somewhat worse than human-written code at Anthropic in late 2025, is roughly at parity as of the report date, and the company expects it to be strictly better within the year.
Mythos Preview Reached 52x Speedup in April 2026
Anthropic runs the same test on every model, handing the AI code that trains a small model and asking it to run faster. Claude Opus 4 averaged a 3x speedup in May 2025. By April 2026, its Mythos Preview model reached 52x. A skilled human needs four to eight hours to achieve 4x, according to the report.
Shown a session before a researcher took a wrong turn, Mythos Preview picked a better next step 64% of the time, up from 51% for Opus 4.5 in November 2025. The company noted that Claude has not yet shown the research judgment to choose which problems matter most.
Anthropic Filed Confidential IPO Registration
Anthropic recently submitted a confidential IPO registration. The company has built its brand around AI safety. The report frames the code contribution trend as a possible path to recursive self-improvement, where AI builds its own successor, though it cautions about current limitations in research judgment.
FAQ
What percentage of Anthropic's production code did Claude write as of May 2026?
Claude authored more than 80% of code merged into Anthropic's production systems as of May 2026, according to the June 4, 2026 Anthropic Institute report. This represents an increase from low single-digit percentages before the February 2025 rollout of an in-house coding agent.
How much faster did Anthropic engineers merge code in Q2 2026 compared to 2024?
Anthropic's typical engineer merged eight times as much code per day in the second quarter of 2026 as in 2024, with human engineers directing and reviewing while Claude performs the writing, according to the company's internal data disclosed in the report.
