Organization

12 Months Ended

Dec. 31, 2018

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization

1. Organization

Description of Business

Gritstone Oncology, Inc. (“Gritstone” or “the Company”) is an immuno-oncology company developing personalized cancer immunotherapies to fight multiple cancer types. The Company was incorporated in the state of Delaware in August 2015, and is based in Emeryville, California and Cambridge, Massachusetts, with a manufacturing facility in Pleasanton, California. The Company operates in one segment.

Initial Public Offering

In October 2018, the Company closed its initial public offering (“IPO”), of 6,854,202 shares of common stock, including 187,535 shares sold pursuant to the underwriters’ partial exercise of their option to purchase additional shares, at an offering price to the public of $15.00 per share. The Company received net proceeds of approximately $92.6 million, after deducting underwriting discounts and commissions and offering costs. In connection with the IPO, all of the Company’s outstanding shares of convertible preferred stock were automatically converted into 19,409,132 shares of common stock. The related carrying value of $177.9 million was reclassified to common stock and additional paid-in capital.

In connection with the completion of its IPO, on October 2, 2018, the Company’s certificate of incorporation was amended and restated to provide for 300,000,000 authorized shares of common stock with a par value of $0.0001 per share and 10,000,000 authorized shares of preferred stock with a par value of $0.0001 per share.