F1This Form 4 is being filed in connection with the sale of shares of Common Stock of WEX Inc. (the "Issuer") by Mustang HoldCo II LLC ("Mustang Holdco II"), the successor in interest to Mustang HoldCo 1 LLC ("Mustang Holdco"). Mustang Holdco II received the shares of Common Stock of the Issuer previously held by Mustang Holdco in a transaction exempt from Section 16 of the Securities Exchange Act of 1934, as amended (the "Exchange Act").
F2The unitholders of Mustang Holdco II are Warburg Pincus Private Equity (Lexington) XI - A, L.P. ("WP XI Lexington-A"), WP (Lexington) Holdings II, L.P. ("WP Lexington II"), Warburg Pincus XI (Lexington) Partners - A, L.P. ("WP XI Lexington Partners-A"), Warburg Pincus XI (E&P) Partners - B, L.P. ("WP XI E&P Partners-B"), WP Mustang Co-Invest LLC ("WP Co-Invest LLC"), WP Mustang Co-Invest-B L.P. ("WP Co-Invest-B"), and WP Mustang Co-Invest-C L.P. ("WP Co-Invest-C").
F3WP Lexington II is the managing member of Mustang Holdco II. Warburg Pincus (E&P) XI, L.P. ("WP E&P XI GP") is (i) the general partner of WP XI Lexington-A, WP Lexington II, WP XI Lexington Partners-A, and WP XI E&P Partners-B, and (ii) the managing member of WP Co-Invest LLC. Warburg Pincus (E&P) XI LLC ("WP E&P XI LLC") is the general partner of WP E&P XI GP. Warburg Pincus Partners (E&P) XI LLC ("WPP E&P XI") is the sole member of WP E&P XI LLC. Warburg Pincus Partners II (US), L.P. ("WP Partners II US") is the managing member of WPP E&P XI. Warburg Pincus & Company US, LLC ("WP & Company US") is the general partner of WP Partners II US. Warburg Pincus LLC ("WP LLC") is the manager of WP XI Lexington-A, WP Lexington II, WP XI Lexington Partners-A, and WP XI E&P Partners-B.
F4Warburg Pincus (Bermuda) XI, Ltd. ("WP Bermuda XI") is the general partner of WP Co-Invest-B and WP Co-Invest-C. Warburg Pincus Partners II (Cayman), L.P. ("WPP II Cayman") is the sole shareholder of WP Bermuda XI. Warburg Pincus (Bermuda) Private Equity GP Ltd. ("WP Bermuda GP") is the general partner of WPP II Cayman. Mustang Holdco II, WP XI Lexington-A, WP Lexington II, WP XI Lexington Partners-A, WP XI E&P Partners-B, WP Co-Invest LLC, WP Co-Invest-B, WP Co-Invest-C, WP E&P XI GP, WP E&P XI LLC, WPP E&P XI, WP Partners II US, WP & Company US, WP Bermuda XI, WPP II Cayman, WP Bermuda GP, and WP LLC are collectively referred to herein as the "Warburg Pincus Entities").
F5Charles R. Kaye and Joseph P. Landy are the Managing Members of WP & Company US, the Co-Chairmen and sole Directors of WP Bermuda GP, and the Managing Members and Co-Chief Executive Officers of WP LLC and, as such, may be deemed to control each of the Warburg Pincus Entities. Messrs. Kaye and Landy disclaim beneficial ownership of all shares of Common Stock of the Issuer held by the Warburg Pincus Entities. Messrs. Kaye and Landy together with the Warburg Pincus Entities are collectively referred to herein as the "Warburg Pincus Reporting Persons". Information with respect to each of the Warburg Pincus Reporting Persons is given solely by such Warburg Pincus Reporting Person, and no Warburg Pincus Reporting Person has responsibility for the accuracy or completeness of information supplied by another Warburg Pincus Reporting Person.
F6By reason of the provisions of Rule 16a-1 of the Exchange Act, the Warburg Pincus Reporting Persons may be deemed to be beneficial owners of the 2,567,207 shares of Common Stock of the Issuer held by Mustang Holdco II. The Warburg Pincus Reporting Persons disclaim beneficial ownership of such shares of Common Stock of the Issuer except to the extent of their direct pecuniary interest therein. As of the date of this filing, this Form 4 shall not be deemed an admission that any reporting person or any other person referred to herein is a beneficial owner of any securities of the Issuer for purposes of Section 16 of the Exchange Act, or for any other purpose, or that any reporting person or other person has an obligation to file this Form 4.
F7The amount of Common Stock reported as beneficially owned by the Warburg Pincus Reporting Persons (other than Mustang Holdco II) and Mustang Holdco (together with such Warburg Pincus Reporting Persons, the "Form 3 Filing Persons") in the Form 3 previously filed with the U.S. Securities and Exchange Commission (the "SEC") on July 15, 2016 (the "Form 3") included 160,862 shares of Common Stock of the Issuer beneficially owned by third parties (the "Other Holders"). The Form 3 Filing Persons had no pecuniary interest in such shares beneficially owned by the Other Holders and disclaimed beneficial ownership of such shares on the Form 3. Such shares are now directly held by the Other Holders, and neither the Form 3 Filing Persons nor Mustang Holdco II, either directly or indirectly, holds such shares as of the transaction referenced in note (1) above.

Remarks

(A) Solely for purposes of Section 16 of the Exchange Act, each of the Warburg Pincus Reporting Persons may be deemed directors-by-deputization by virtue of certain Warburg Pincus Reporting Persons' (and certain affiliates of WP LLC to whom shares of Common Stock of the Issuer are transferred) contractual right to appoint a director to the board of directors of the Issuer. As a result, the "Director" box is marked in Item 5 of this Form 4. (B) Due to the limitations on the number of Reporting Persons allowed on each Form 4, WP E&P XI GP, WP E&P XI LLC, WPP E&P XI, WP Partners II US, WP & Company US, WP Bermuda XI, WPP II Cayman, WP Bermuda GP, and WP LLC are filing a separate Form 4. (C) Entity names in the signature blocks have been abbreviated. Please refer to Notes (1), (2), (3), and (4) of this Form 4 for the complete legal name of such entities. *The Powers of Attorney given by each of Mr. Kaye and Mr. Landy were previously filed with the SEC on July 11, 2016 (with a revised filing date of July 12, 2016) as exhibits 99.2 and 99.3 to the statement on Schedule 13D filed by WP LLC with respect to the Issuer and are hereby incorporated by reference.