K2 neutral strain Saccharomyces cerevisiae USM12 was identified and characterized. This strain carried an M double‐stranded RNA (dsRNA) genome encoding for resistance to K2 toxin. The M dsRNA was larger than the K2 killer yeast M dsRNA and homoduplex analysis of denatured and reannealed K2 neutral M dsRNA revealed an inverted duplication. Heteroduplex analysis showed that two thirds of the K2 M genome had homology with K2 neutral M genome. Hybridization showed that the USM12 M dsRNA has significant homology with the K2M dsRNA. Protein profiles of extracellular proteins from USMA12 and cured strain indicated that USM12 did not secrete any toxin. This is the first time that a K2 neutral yeast strain has been characterized.