X0508 4 2026-02-16 0001587732 ONE Gas, Inc. OGS 0001595607 McCormick Joseph L 15 E. 5TH STREET TULSA OK 74103 false true false false See Remarks false Common stock, par value $0.01 2026-02-16 4 M false 3803.8 86.04 A 76515.310 D Common stock, par value $0.01 2026-02-16 4 F false 1608.290 86.04 D 74907.020 D Common stock, par value $0.01 3697 I by 401(k) Plan Performance Units 2023 2026-02-16 4 M false 4891 86.04 D Common stock, par value $0.01 4891 0 D Performance units awarded under the Issuer's Amended and Restated Equity Compensation Plan (2018). The award, including dividend equivalents, vested on a prorated basis upon the reporting person's December 9, 2025, retirement pursuant to the terms of the award agreement. The award vested on February 14, 2026, in an amount equal to 76% of the performance units awarded based upon Issuer's total shareholder return compared to the total shareholder return of a selected peer group, was certified by the Executive Compensation Committee of the Board of Directors on February 16, 2026, and issued pursuant to the terms of the grant agreement. Former Senior Vice President, General Counsel and Assistant Secretary /s/ Brian K. Shore, Attorney-in-Fact for Joseph L. McCormick 2026-02-19