Filing Details

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 1)* Midcoast Energy Partners LP (Name of Issuer) Common (Title of Class of Securities) 59564N103 (CUSIP Number) Clinton Ward, Chief Compliance Officer, 3290 Northside Parkway, 7th Floor, Atlanta, GA 30327 (404)881-3401 (Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications) December 31, 2016 (Date of Event which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuant to which this Schedule is filed: X Rule 13d-1(b) Rule 13d-1(c) Rule 13d-1(d) * 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). CUSIP No.59564N103 13G Page 2 of 5 Pages 1. NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Atlantic Trust Group LLC 04-3173832 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a) (b) 3. SEC USE ONLY 4. CITIZENSHIP OR PLACE OF ORGANIZATION Delaware NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH 5. SOLE VOTING POWER 1,368,300 6. SHARED VOTING POWER 0 7. SOLE DISPOSITIVE POWER 1,368,300 8. SHARED DISPOSITIVE POWER 0 9. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,368,300 10. CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions) 11. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 6.05% 12. TYPE OF REPORTING PERSON (see instructions) Parent holding company or control person in accordance with section 240.13d-1(b)(1)(ii)(G)

CUSIP No.59564N103 13G Page 3 of 5 Pages Item 1. (a) Name of Issuer Midcoast Energy Partners LP (b) Address of Issuers Principal Executive Offices 1100 Louisiana Street, Suite 3300 Houston, TX 77002 Item 2. (a) Name of Person Filing Atlantic Trust Group LLC (b) Address of the Principal Office or, if none, residence 3290 Northside Parkway, 7th Floor, Atlanta, GA 30327 (c) Citizenship Delaware (d) Title of Class of Securities Common (e) CUSIP Number 59564N103 Item 3. If this statement is filed pursuant to section 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a: (a) Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o). (b) Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c). (c) Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c). (d) Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8). (e) An investment adviser in accordance with section 240.13d-1(b)(1)(ii)(E); (f) An employee benefit plan or endowment fund in accordance with section 240.13d-1(b)(1)(ii)(F); (g) X A parent holding company or control person in accordance with section 240.13d-1(b)(1)(ii)(G); (h) A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813); (i) A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3); (j) Group, in accordance with section 240.13d-1(b)(1)(ii)(J). Item 4. Ownership. Provide the following information regarding the aggregate number and percentage of the class of securities of the issuer identified in Item 1. (a) Amount beneficially owned: 1,368,300 CUSIP No.59564N103 13G Page 4 of 5 Pages (b) Percent of class: 6.05% (c) Number of shares as to which the person has 0 (i) Sole power to vote or to direct the vote 1,368,300 (ii) Shared power to vote or to direct the vote 0. (iii) Sole power to dispose or to direct the disposition of 1,368,300 (iv) Shared power to dispose or to direct the disposition of 0. Instruction. For computations regarding securities which represent a right to acquire an underlying security see section 240.13d-3(d)(1). Item 5. Ownership of Five Percent or Less of a Class. If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following Instruction. Dissolution of a group requires a response to this item. Item 6. Ownership of More than Five Percent on Behalf of Another Person. Item 7. Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company. Atlantic Trust Company, N.A. AT Investment Advisors, Inc. Item 8. Identification and Classification of Members of the Group. Item 9. Notice of Dissolution of Group. Item 10. Certification. (a) The following certification shall be included if the statement is filed pursuant to section 240.13d-1(b): By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect. (b) The following certification shall be included if the statement is filed pursuant to section 240.13d-1(c): By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect. CUSIP No.59564N103 13G Page 5 of 5 Pages 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. 02/13/2017 Date /s/ Mary E. Antunes Signature Mary E. Antunes / Senior Compliance Officer Name/Title