K2M Group Holdings Inc. said Welsh, Carson, Anderson & Stowe XI LP and certain related affiliates proposed an offering of 4 million of K2M common shares.

The underwriter has an option to purchase up to 600,000 additional common shares from the selling stockholders on a pro rata basis.

K2M will not receive any proceeds from the sale, which is expected to close on or about Feb. 1, subject to customary closing conditions.

Piper Jaffray & Co. will act as sole book-running manager and underwriter for the offering.