Michael B. Barry

Samlyn Capital, LLC

500 Park Avenue, 2^nd Floor

New York, NY 10022

Tel: +1 (212) 588-9098

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

Notices and Communications)

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

The funds for the purchase of the 48,092,329 Shares beneficially owned by Samlyn Capital, Samlyn LP and Mr. Pohly came from the working capital of Samlyn Onshore Fund and Samlyn Offshore Master Fund, which are the direct owners of the Shares. No borrowed funds were used to purchase the Shares, other than any borrowed funds used for working capital purposes (including certain leverage arrangements) in the ordinary course of business.

The funds for the purchase of the 17,093,076 Shares beneficially owned by Samlyn Partners and Samlyn Onshore Fund came from the working capital of Samlyn Onshore Fund, which is the direct owner of the Shares. No borrowed funds were used to purchase the Shares, other than any borrowed funds used for working capital purposes (including certain leverage arrangements) in the ordinary course of business.

The funds for the purchase of the 30,999,253 Shares beneficially owned by Samlyn Offshore Master Fund came from its working capital. No borrowed funds were used to purchase the Shares, other than any borrowed funds used for working capital purposes (including certain leverage arrangements) in the ordinary course of business.

In addition, Item 3 and Item 4 of the Amendment No. 1 to Schedule 13D filed with the SEC in respect of the Issuer on November 6, 2014 by Samlyn Capital, Samlyn Partners, Samlyn Onshore Fund, Samlyn Offshore Master Fund, Ltd., and Robert Pohly (“Amendment No. 1”) are incorporated herein by reference.

The Reporting Persons are filing this Amendment No. 4 to Schedule 13D to report that Michael B. Barry, General Counsel and Chief Compliance Officer of Samlyn Capital, was appointed to the Issuer’s board of directors (the “Board”) on April 30, 2018. Mr. Barry was nominated to the Board pursuant to the exercise of rights granted under the terms of the Director Nomination Agreement dated December 22, 2011 by and among the Issuer, Samlyn Onshore Fund and Samlyn Offshore Master Fund that was summarized and incorporated by reference into Amendment 1.

As compensation for Michael B. Barry’s service on the Board, on April 30, 2018 (the “Grant Date”), the Issuer granted to (i) Samlyn Offshore Master Fund options to purchase 259,027 Shares, and (ii) Samlyn Onshore Fund options to purchase 88,195 Shares. The stock options have an exercise price of $0.06 per share and expire on April 29, 2023. In respect of Samlyn Offshore Master Fund, 103,611 of the stock options vested on April 30, 2018, and the remaining stock options will vest on July 1, 2018 (unless earlier terminated due to the termination of Michael B. Barry’s service as a member of the Board). In respect of Samlyn Onshore Fund, 35,278 of the stock options vested on April 30, 2018, and the remaining stock options will vest on July 1, 2018 (unless earlier terminated due to the termination of Michael B. Barry’s service as a member of the Board).

Except as otherwise set forth herein, the Reporting Persons do not have any present plans or proposals which would relate to, or result in, the matters set forth in subparagraphs (a) – (j) of Item 4 of Schedule 13D. However, subject to market conditions and in compliance with applicable securities laws, the Reporting Persons reserve the right, at a later date, to effect one or more of such changes or transactions in the number of Shares they may be deemed to beneficially own in open-market transactions or privately negotiated transactions. The Reporting Persons may also communicate with the Issuer’s management, the Issuer’s board of directors and other holders of Shares from time to time.

As of the date hereof, Samlyn Capital, Samlyn LP and Mr. Pohly may each be deemed to be the beneficial owner of 48,092,329 Shares, constituting 25.6% of the Shares, based upon 187,969,462 Shares outstanding as of the date hereof, as adjusted for Series A Convertible Notes, stock options and warrants of the Issuer beneficially owned by Samlyn Capital, Samlyn LP and Mr. Pohly. Each of Samlyn Capital, Samlyn LP and Mr. Pohly has the sole power to vote or direct the vote of 0 Shares and the shared power to vote or direct the vote of 48,092,329 Shares. Each of Samlyn Capital, Samlyn LP and Mr. Pohly has the sole power to dispose or direct the disposition of 0 Shares and the shared power to dispose or direct the disposition of 48,092,329 Shares.

As of the date hereof, Samlyn Partners and Samlyn Onshore Fund may each be deemed to be the beneficial owner of 17,093,076 Shares, constituting 10.5% of the Shares, based upon 163,453,652 Shares outstanding as of the date hereof, as adjusted for a Series A Convertible Note, stock options and warrants of the Issuer beneficially owned by Samlyn Partners and Samlyn Onshore Fund. Each of Samlyn Partners and Samlyn Onshore Fund has the sole power to vote or direct the vote of 0 Shares and the shared power to vote or direct the vote of 17,093,076 Shares. Each of Samlyn Partners and Samlyn Onshore Fund has the sole power to dispose or direct the disposition of 0 Shares and the shared power to dispose or direct the disposition of 17,093,076 Shares.

As of the date hereof, Samlyn Offshore Master Fund may be deemed to be the beneficial owner of 30,999,253 Shares, constituting 17.7% of the Shares, based upon 174,904,359 Shares outstanding as of the date hereof, as adjusted for a Series A Convertible Note, stock options and warrants of the Issuer beneficially owned by Samlyn Offshore Master Fund. Samlyn Offshore Master Fund has the sole power to vote or direct the vote of 0 Shares and the shared power to vote or direct the vote of 30,999,253 Shares. Samlyn Offshore Master Fund has the sole power to dispose or direct the disposition of 0 Shares and the shared power to dispose or direct the disposition of 30,999,253 Shares.

Other than the stock options granted to Samlyn Offshore Master Fund and Samlyn Onshore Fund as described in Item 4 above, there have been no transactions in the Shares by the Reporting Persons during the past sixty days.

The disclosures regarding the Director Nomination Agreement set forth in Item 4 and Item 6 of the Schedule 13D filed with the SEC in respect of the Issuer on January 3, 2012 by Samlyn Capital, Samlyn Partners, Samlyn Onshore Fund, Samlyn Offshore Master Fund, Ltd., and Robert Pohly (the “Initial Schedule 13D”) are incorporated herein by reference.

The form of the Director Nomination Agreement that was incorporated by reference as Exhibit 10.5 to Item 7 of the Initial Schedule 13D is incorporated herein by reference.

The disclosures regarding the Investment Agreement, the Convertible Notes, the Warrant Cancellation Agreement and the A&R Registration Rights Agreement set forth in Item 4 and Item 6 of Amendment No. 1 are incorporated herein by reference.

The form of the Investment Agreement, form of the Convertible Notes, form of the Warrant Cancellation Agreement and form of the A&R Registration Rights Agreement that were incorporated by reference as separate exhibits to Item 7 of Amendment No. 1 are also incorporated herein by reference.

The disclosures regarding the Series A Agreement set forth in Item 4 and Item 6 of the Amendment No. 3 to Schedule 13D filed with the SEC in respect of the Issuer on December 18, 2017 by the Reporting Persons (the “Amendment No. 3”) are incorporated herein by reference.

The form of the Series A Agreement that was incorporated by reference as Exhibit B to Item 7 of Amendment No. 3 is incorporated herein by reference.

The information set forth in Item 4 above is incorporated by reference in its entirety in this Item 6.

Other than as set forth above, the Reporting Persons do not have any contract, arrangement, understanding or relationship with any person with respect to securities of the Issuer.

Exhibit A: Joint Filing Agreement