 Magenta Therapeutics, Inc. Nasdaq: MGTA, a clinical-stage biotechnology company developing novel medicines to bring the curative power of stem cell transplant to more patients, announced that it has commenced an underwritten public offering of 60 million of its common stock. Magenta also intends to grant the underwriters a 30-day option to purchase up to an additional fifteen percent 15 of the shares of common stock offered in the public offering. All of the shares in the proposed offering are to be sold by Magenta. 