United States SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ☒ Annual Report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the fiscal year ended June 30, 2021 ☐ Transition report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the transition period from to . Commission File Number: 001-39375 II-VI INCORPORATED (Exact name of registrant as specified in its charter) Pennsylvania 25-1214948 (State or other jurisdiction of incorporatio ...