Under the Securities Exchange Act of 1934
(Amendment No. 4)*

(Name of Issuer)

(Title of Class of Securities)

(CUSIP Number of Class of Securities)

(Name, Address and Telephone Number of Person
Authorized to Receive Notices and Communications)

(Date of Event Which Requires Filing of this Statement)

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 §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box. o

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See § 240.13d-7(b) for other parties to whom copies are to be sent.

*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).

(1)           Based on 51,012,890 shares of Common Stock issued and outstanding as of December 20, 2013 plus 257,058 shares of Common Stock underlying warrants exercisable for shares of Common Stock of the Company.

2

This Amendment No. 4 (the “Amendment”) relates to the Statement of Beneficial Ownership on Schedule 13D filed jointly by Wellington Management Company, LLP (“Wellington Management”), Wellington Hedge Management, LLC (“WHML”) and Wellington Hedge Administrator, LLC (“WHAL”) with the SEC on February 8, 2013, as amended by Amendment No. 1 to such statement filed with the SEC on October 29, 2013, Amendment No. 2 to such statement filed with the SEC on November 14, 2013 and Amendment No. 3 to such statement filed with the SEC on November 27, 2013 (as further amended by this Amendment, the “Schedule 13D”).  As indicated in Item 5(e) of Amendment No. 3, WHML and WHAL are no longer Reporting Persons with respect to this Schedule 13D.

Except as set forth below, all Items of the Schedule 13D remain unchanged.  All capitalized terms not otherwise defined herein shall have the meanings given to such terms in the Schedule 13D.

ITEM 5.                                                INTEREST IN SECURITIES OF THE ISSUER

Item 5 of Schedule 13D is hereby amended to add the following information:

(a)         and (b)                                 As of the date hereof:

Wellington Management, in its capacity as investment adviser, may be deemed to be the beneficial owner of 2,995,481 shares of Common Stock, consisting of (i) 2,738,423 shares of Common Stock held by the Clients and (ii) 257,058 shares of Common Stock underlying warrants held by the Clients.  Such shares represent beneficial ownership of 5.8% of the Common Stock, based on 51,012,890 shares of Common Stock issued and outstanding as of December 20, 2013.  The foregoing excludes 536,231 shares of Common Stock held in the indemnity escrow, registered in the name of the escrow agent, to secure (A) any post-closing purchase price adjustment due to the Company from Row 44 pursuant to the terms of the Merger Agreement and (B) Row 44’s indemnification obligations under the Merger Agreement.

The Reporting Person has shared power to vote or direct the vote and to dispose or direct the disposition of shares of Common Stock beneficially owned by the Reporting Person as indicated herein.

(c)                                  Except as set forth on Schedule A attached hereto, no transactions were effected by the Reporting Persons since the filing of Amendment No. 3 to the Schedule 13D through December 20, 2013.  All of the transactions set forth on Schedule A were effected in the ordinary course of business of the Reporting Person on behalf of its Clients.  The transactions set forth in Schedule A were effected in open market transactions on the Nasdaq Capital Market.

3

SIGNATURE

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

4

Schedule A

5