Acquisition of Ceiba and Okume Expands and Diversifies Production In October 2017, Kosmos announced that, in partnership with Trident Energy, it agreed to acquire an interest in three exploration licenses (Blocks W, S, and EG-21), as well as Hess Corporation’s interest in the adjacent Ceiba Field and Okume Complex assets offshore Equatorial Guinea on a 50-50 basis. Under the terms of the agreements, Kosmos is primarily responsible for exploration and subsurface evaluation while Trident is primarily responsible for production operations and optimization. The transactions capture a material position in a proven but under-explored oil basin originally discovered and operated by members of the Kosmos management team. The transaction expanded our position in the Gulf of Guinea and provides immediate cash flow through existing production with upside potential from optimizing production operations, infill drilling, and step-out exploration opportunities with the potential for low cost tie-backs through existing infrastructure. The original Ceiba and Okume discoveries de-risked the key play elements in the Rio Muni basin, but limited exploration in subsequent years means Kosmos now has the chance to unlock the full exploration potential of the basin. The gross acquisition price of $650 million was effective as of January 1, 2017. Kosmos paid net cash consideration of approximately $231 million from cash on hand and proceeds from the company’s reserve-based lending facility at close on November 28, 2017. Oil production from the Ceiba Field and Okume Complex has averaged approximately 45,000 bopd gross during the period Kosmos has held an interest. 4 EQUATORIAL GUINEA 40 miles 50 km BLOCK W EG-21 EQUATORIAL GUINEA GABON BLOCK S Gulf of Guinea OKUME CEIBA EQUATORIAL GUINEA EXPLORATION