UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934

MDC Partners Incorporated
(Name of Issuer)

COM
(Title of Class of Securities)

552697104
(CUSIP Number)

12/31/2018
(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

  ☑
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 the disclosures provided in a prior cover page.

The information required in 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. 552697104

1
NAMES OF REPORTING PERSONS
 
 
I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
 
 
Schroder Investment Management North America Inc.
 
 
 
 
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
 
 
United States
 
 
 
 
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH
5
SOLE VOTING POWER
 
 
3,038,727
 
 
 
 
6
SHARED VOTING POWER
 
 
0
 
 
 
 
7
SOLE DISPOSITIVE POWER
 
 
3,038,727
 
 
 
 
8
SHARED DISPOSITIVE POWER
 
 
0
 
 
 
 
9
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
 
 
3,038,727
 
 
 
 
10
CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)
 
 
☐
 
 
 
 
11
PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)
 
 
5.284% of outstanding shares
 
 
 
 
12
TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)
 
 
IA
 
 
 
 

2
Item 1.

 
(a)
Name of Issuer
MDC Partners Incorporated (COM)
 
(b)
Address of Issuer’s Principal Executive Offices
745 5th Avenue, 19th Fl New York, NY 10151

Item 2.

 
(a)
Name of Person Filing
Schroder Investment Management North America Inc
 
(b)
Address of Principal Business Office or, if none, Residence
7 Bryant Park, 19th Floor
New York, NY 10018
 
(c)
Citizenship
USA
 
(d)
Title of Class of Securities
COM
 
(e)
CUSIP Number
552697104

Item 3.
If this statement is filed pursuant to §§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 §240.13d-1(b)(1)(ii)(E);
       
 
(f)
 ☐
An employee benefit plan or endowment fund in accordance with §240.13d-1(b)(1)(ii)(F);
       
 
(g)
 ☐
A parent holding company or control person in accordance with § 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 §240.13d-1(b)(1)(ii)(J).

3
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:    3,038,727
 
(b)
Percent of class:    5.284% of outstanding shares
 
(c)
Number of shares as to which the person has:
   
(i)
Sole power to vote or to direct the vote
0
   
(ii)
Shared power to vote or to direct the vote
3,038,727
   
(iii)
Sole power to dispose or to direct the disposition of
0
   
(iv)
Shared power to dispose or to direct the disposition of
3,038,727

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   ☐.

Not applicable.

Item 6.
Ownership of More than Five Percent on Behalf of Another Person

Not applicable.

Item 7.
Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company

Not applicable.

Item 8.
Identification and Classification of Members of the Group

Schroder Investment Management North America Inc. is a registered investment adviser with its respective home country regulator.  Schroder Investment Management North America Inc. is located in the United States at7 Bryant Park, 19th Floor, New York, NY 10018.

Item 9.
Notice of Dissolution of Group

Not applicable.

Item 10.
Certification

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.

4
After reasonable inquiry and to the best of its knowledge and belief, the undersigned certifies that the information set forth in this statement is true, complete and correct.

 
February 7, 2019
   
 
By:
/s/ Karl Dasher
  
 
Name:
Karl Dasher**
 
Title:
Chief Executive Officer
     
 
Schroder Investment Management North America Inc
   
 
** Authorized to sign on behalf of the following Advisor:
Schroder Investment Management Ltd


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