UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q þ Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the Quarterly Period Ended March 31, 2019 ¨ 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 001-35406 Illumina, Inc. (Exact name of registrant as specified in its charter) Delaware 33-0804655 (State or other jurisdiction of incorporation ...