At Google I/O, Sundar Pichai gave developers a short wait: Gemini 3.5 Pro would arrive the next month. That window has passed. Bloomberg-linked reports now point to coding performance as the reason the flagship Pro model is still not broadly available.
The tension is sharper because Google has already turned AI coding into an internal production habit. At Cloud Next, the company said 75% of new Google code is AI-generated and approved by engineers, up from 50% last fall. The public Pro model, however, is stuck on the same capability line.
"We're currently testing 3.5 Pro, an upgraded Flash model, and other models with partners, and we're productively engaged with the U.S. government."
Coding is the bottleneck
9to5Google noted that Google said at I/O that Gemini 3.5 Pro would follow in June. CNA and Reuters reported that the model is months behind schedule while Google works to improve its capabilities, especially coding. The same report said Google updated the data used to train Gemini late last month, but the results missed expectations.
This is not a routine calendar slip. Coding agents have become the enterprise wedge for frontier models. Claude Code, GPT-5.6 and Grok 4.5 all compete on long-running code work, tool use and debugging. If Gemini 3.5 Pro cannot show strength there, Google has to lean harder on ecosystem reach.
The market reacted first
MarketWatch said Alphabet shares fell more than 4% on Thursday. IBD put the decline at 4.4% to $354.46, while CNA/Reuters used a nearly 3% intraday figure. The exact market window differs, but the signal is consistent: investors treated the delay as a risk to Google's AI cadence.
The careful reading is narrower. Google has not confirmed the “months behind” phrasing, and its public statement says testing continues with partners. The next concrete signs are a new launch window, whether upgraded Flash carries more enterprise work first, and what management says on Alphabet's July 22 earnings call.
Sources: Google I/O and Cloud Next announcements, Reuters/CNA, 9to5Google, MarketWatch, CocoLoop, Investor's Business Daily; checked the Gemini 3.5 Pro launch window, training-data update, employee-source count, stock-move figures and internal AI-generated-code metric.