Oil market watchers may be closely tracking the slug of production Opec-plus is returning to market, but their sights should also be set on Guyana, where US major Exxon Mobil has once again brought a deepwater development on line ahead of schedule. The four-month expedited start of the 250,000 barrel per day Yellowtail development will have an even more pronounced impact on market balances should Exxon rapidly reach peak output — a safe assumption given its track record. Yellowtail, which delivered first oil earlier this month, hosts the largest floating production, storage and offloading vessel (FPSO) deployed on the Exxon-operated Stabroek Block, home to an estimated 11 billion barrels of oil equivalent of recoverable resources. The start-up of Stabroek's fourth FPSO — coming just a decade after the block's initial discovery — marks the halfway point in Exxon's upsized eight-FPSO development plan through 2030. Yellowtail's start-up coincides with Opec-plus completing the unwinding of 2.2 million b/d of voluntary production cuts, with significant implications for global oil supply heading into 2026. Exxon's third Guyana FPSO — installed at Payara — reached peak output less than three months after first oil.