Citigroup has invested in Sakana AI, marking the US banking group’s first such investment in Japan.

The investment size was not disclosed, though both sides described it as “strategic”.

In separate statements, the companies said the tie-up is aimed at speeding up innovation in global financial services by tapping into Sakana AI’s research and development capabilities.

The bank made the investment through its Markets Strategic Investments arm.

Citi Markets Strategic Investments global head Siris Singh said: “Sakana AI has developed a unique and robust offering that have enabled them to develop a strong foundation and proven product market fit in Japan.”

The Tokyo-based AI start-up specialises in building new types of foundational models and enterprise-grade AI tools based on nature-inspired intelligence.

It plans to deploy the fresh capital to speed up its international expansion.

“Leveraging our expertise in applying frontier AI within specialised financial domains, we look forward to working with Citi to transform global financial services,” Sakana AI CEO David Ha said.

In 2025, Sakana AI announced partnerships with Mitsubishi UFJ Financial Group (MUFG) and Daiwa Securities Group to develop custom AI models tailored to specialised financial domains.

In November, Santander Group also invested in the start-up. Like Citi, the Spanish bank’s infusion was part of Sakana AI’s Series B fundraising.

Other US banking majors have also ramped up their AI push.

In December, Reuters, citing Wells Fargo CEO Charlie Scharf, reported the bank is anticipating further reductions in its workforce, while planning to roll out AI tools incrementally through 2026 and beyond to boost efficiency.

While Scharf said AI is not expected to replace human staff entirely, he indicated it would change how work is carried out across the organisation.

Meanwhile, JPMorgan Chase CEO Jamie Dimon has highlighted plans for worker redeployment amid AI adoption, according to CNBC.