Securities registered pursuant to section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes o    No x

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes o    No x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes x    No o

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§ 229.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files). Yes x    No o

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K (§ 229.405 of this chapter) is not contained herein, and will not be contained, to the best of registrant's knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K. o

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. o

Indicate by check mark whether the registrant is a shell company (as defined by Rule 12b-2 of the Act). Yes o    No x

The aggregate market value of the voting stock held by non-affiliates of the registrant as of June 30, 2017, the last business day of the registrant's most recently completed second fiscal quarter, was approximately $343,111,833 (computed by reference to the price at which the registrant's common stock was last sold on such date, as reported by The Nasdaq Global Select Market). Shares of common stock held by the registrant's officers and directors and beneficial owners of 10% or more of the outstanding shares of the registrant's common stock have been excluded from the calculation of this amount because such persons may be deemed to be affiliates of the registrant; however, the treatment of these persons as affiliates of the registrant for purposes of the calculation of this amount is not, and shall not be considered, a determination as to whether any such person is an affiliate of the registrant for any other purpose.

As of March 6, 2018, the number of outstanding shares of the registrant's common stock was 152,394,550.

Portions of the registrant's definitive proxy statement for its 2018 annual meeting of stockholders are incorporated in Part III of this report by reference, to the extent stated therein.

(a)(1) Consolidated Financial Statements

(a)(2) Financial Statement Schedules

(a)(3) Exhibits