PNM Resources engages in the energy and energy-related businesses. It operates through Public Service Company of New Mexico (PNM) and Texas-New Mexico Power Company (TNMP) segments. The PNM segment is primarily involved in the generation, transmission, and distribution of electricity. It generates electricity using coal, natural gas and oil, nuclear fuel, solar, wind, and geothermal energy sources. The TNMP segment provides regulated transmission and distribution services.