Google’s next flagship AI model has reportedly been delayed by several months after failing to meet the company’s internal performance targets.

Gemini 3.5 Pro, which Google had previously said would arrive in June, remains in testing as engineers work to improve its capabilities, particularly its ability to generate software code.

The delay has reportedly frustrated engineers, researchers and managers inside Google, with some concerned the company is losing ground to rivals including OpenAI, Anthropic and Meta.

Google updated the data used to train Gemini 3.5 Pro late last month in an attempt to improve its coding performance, but the results reportedly fell short of expectations.

Alphabet shares fell following news of the setback.

Google’s sprawling corporate structure is said to be contributing to the delays, with teams across Google Cloud, DeepMind, Android and other divisions developing overlapping AI coding tools.

“We’re shipping quickly across a wide range of models while keeping them highly cost-effective for customers,” a Google spokesperson said.

“We’re currently testing 3.5 Pro, an upgraded Flash model, and other models with partners, and we’re productively engaged with the US government on model testing and broader frameworks.”

Google’s sprawling corporate structure may be contributing to the delays, with teams across Google Cloud, DeepMind, Android and other divisions developing overlapping AI coding tools.

Several layers of executives and product teams are also involved in preparing new Gemini models for release across products including Search, YouTube and Maps.

Google has moved to consolidate some of its coding tools and recently formed a dedicated team inside DeepMind to focus on AI-assisted software development.

The company claims 75% of its new code is now generated by AI before being reviewed and approved by engineers, although employees reportedly continue to face restrictions and computing capacity constraints when using internal AI systems.

Gemini 3.5 Flash was unveiled at Google I/O in May and has since been adopted by companies including design platform Figma.

But some business customers reportedly consider the model slower and more expensive than earlier versions, while still falling behind premium models offered by competitors.

Google has not provided a revised release date for Gemini 3.5 Pro.