UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

SCHEDULE 13D/A

Under The Securities Exchange Act of 1934

(Amendment No. 3)*

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of ss.240.13D-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box ¨.

*   The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

ITEM 1. Security and Issuer

This Amendment No. 3 to Schedule 13D (this “Third Amendment”) amends and supplements the statement on Schedule 13D filed by the Reporting Persons (as defined below) on July 10, 2009 with the U.S. Securities and Exchange Commission (the “SEC”), as amended by Amendment No. 1 to Schedule 13D filed by the Reporting Persons on December 20, 2010 and Amendment No. 2 to Schedule 13D filed by the Reporting Persons on May 31, 2011 (collectively, the “Schedule 13D”). Capitalized terms used but not defined herein have the meanings given to such terms in the Schedule 13D. Except as otherwise provided in this Third Amendment, all Items of the Schedule 13D remain unchanged.

ITEM 2.   Identity and Background.

Parts (a), (b), (c) and (f) of Item 2 of the Schedule 13D are hereby amended and supplemented, with effect from the date of this Third Amendment, by adding the following:

This Third Amendment is being filed jointly by (i) K Equity, LLC, a Delaware limited liability company (“K Equity”), (ii) K Holdings, LLC, a Delaware limited liability company, (iii) Platinum Equity Capital Partners II, L.P., a Delaware limited partnership, (iv) Platinum Equity Partners II, LLC, a Delaware limited liability company, (v) Platinum Equity Investment Holdings II, LLC, a Delaware limited liability company, (vi) Platinum Equity, LLC, a Delaware limited liability company, and (vii) Tom Gores, an individual (collectively, the “Reporting Persons”).

ITEM 3.   Source and Amount of Funds or Other Consideration.

Item 3 of the Schedule 13D is hereby amended and supplemented, with effect from the date of this Third Amendment, by adding the following:

The information in Item 6 of this Third Amendment is incorporated herein by reference.

ITEM 4.   Purpose of Transaction.

Item 4 of the Schedule 13D is hereby amended and supplemented, with effect from the date of this Third Amendment, by adding the following:

The information in Item 6 of this Third Amendment is incorporated herein by reference.

ITEM 5.   Interests in Securities of the Issuer.

Parts (a) and (b) of Item 5 of the Schedule 13D are hereby amended and supplemented, with effect from the date of this Third Amendment, by adding the following:

The information in Item 6 of this Third Amendment is incorporated herein by reference.

ITEM 6.   Contracts, Arrangements, Understandings or Relationships with Respect to Securities of the Issuer.

Item 6 of the Schedule 13D is hereby amended and supplemented, with effect from the date of this Third Amendment, by adding the following:

Additional Subsequent Events

On September 6, 2017, K Equity and the Company entered into an underwriting agreement (the “Underwriting Agreement”) with UBS Securities LLC (the “Underwriter”). Pursuant to the terms of the Underwriting Agreement, the Underwriter agreed to purchase from K Equity its common stock warrant, dated May 31, 2011, to purchase 8,416,814 shares of common stock of the Company (the “Warrant”).

Pursuant to the Underwriting Agreement, on September 11, 2017, K Equity sold the Warrant to the Underwriter for a price equal to $20.52 per share of underlying common stock of the Company. As a result of the foregoing sale of the Warrant to the Underwriter, K Equity no longer beneficially owns any shares of common stock of the Company on a post-sale basis.

The foregoing description of the Underwriting Agreement is qualified in its entirety by reference to the full text thereof, which is included as Exhibit 8 hereto, and is incorporated herein by reference.

ITEM 7.   Material to be Filed as Exhibits.

Item 7 of the Schedule 13D is hereby amended and supplemented, with effect from the date of this Third Amendment, by adding the following:

SIGNATURE

After reasonable inquiry and to the best of our knowledge and belief, the undersigned certify that the information set forth in this statement is true, complete and correct.

Dated: September 13, 2017

Exhibit Index