Isochronal annealing of Co66Ni12Si9B13 metallic glass leads to the formation of the α-Co and Co x B (x=2,3) phases at 673 K and 773 K, respectively. The abrupt decrease of the electrical and Hall resistivities and spontaneous Hall coefficient was observed due to formation of the crystalline phases. The phases were identified by X-ray diffraction and confirmed with the use of a quantum chemistry method.PACS : 64.70.Pf