A steel alloy for a bearing, the alloy having a composition having from 0.04 to 0.1 wt. % carbon, from 10.5 to 13 wt. % chromium, from 1.5 to 3.75 wt. % molybdenum, from 0.3 to 1.2 wt. % vanadium, from 0.3 to 2.0 wt .% nickel, from 6 to 9 wt. % cobalt, from 0.05 to 0.4 wt. % silicon, from 0.2 to 0.8 wt. % manganese, from 0.02 to 0.06 wt. % niobium, from 0 to 2.5 wt. % copper, from 0 to 0.1 wt. % aluminium, from 0 to 250 ppm nitrogen, from 0 to 30 ppm boron, and the balance iron, together with any unavoidable impurities.