UNITED STATES Title of each class: Trading Symbol(s) Name of each exchange on which registered: Common stock, $0.001 par value per share IDEX The Nasdaq Stock Market SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q x QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2019 ¨ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from __________ to _______ ...