UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

(Rule 13d-101)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT

TO § 240.13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO

§ 240.13d-2(a)

(Amendment No. 4) 1

Managed Duration Investment Grade Municipal Fund

(Name of Issuer)

Common Stock

(Title of Class of Securities)

56165R103

(CUSIP Number)

Daniel Lippincott, Senior Tax-Sensitive Manager

Karpus Management, Inc.

d/b/a Karpus Investment Management

183 Sully’s Trail

Pittsford, New York 14534

(585) 586-4680

Adam W. Finerman, Esq.

Olshan Frome Wolosky LLP

1325 Avenue of the Americas

New York, New York 10019

(212) 451-2300

(Name, Address and Telephone Number of Person

Authorized to Receive Notices and Communications)

July 30, 2018

(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 x.

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

_______________

1 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. 56165R103

1	NAME OF REPORTING PERSON Karpus Investment Management
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) x (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS WC
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)		¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION NEW YORK
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER 489,053
	8	SHARED VOTING POWER -
	9	SOLE DISPOSITIVE POWER 489,053
	10	SHARED DISPOSITIVE POWER -
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 489,053
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES		o
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 7.19%
14	TYPE OF REPORTING PERSON IA

CUSIP NO. 56165R103

1	NAME OF REPORTING PERSON George W. Karpus
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) x (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS PF
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)		¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION USA
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER 8,268
	8	SHARED VOTING POWER 0
	9	SOLE DISPOSITIVE POWER 8,268
	10	SHARED DISPOSITIVE POWER 0
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 14,893
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES		o
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) Less than 1%
14	TYPE OF REPORTING PERSON IN

CUSIP NO. 56165R103

The following constitutes Amendment No. 4 to the Schedule 13D filed by the undersigned ("Amendment No. 4"). This Amendment No. 4 amends the Schedule 13D as specifically set forth herein.

Item 3.

Source and Amount of Funds or Other Consideration.

Item 3 is hereby amended and restated to read as follows:

Karpus, an independent registered investment advisor, has accumulated (i) 0 Shares directly, and (ii) 635,623 Shares on behalf of accounts that are managed by Karpus (the “Accounts”) under limited powers of attorney, which represents 7.19% of the outstanding Shares. All funds that have been utilized in making such purchases for the Accounts (which are open market purchases unless otherwise noted) are from such Accounts.

The aggregate purchase price of the 489,053 Shares beneficially owned by Karpus is approximately $6,704,018, excluding brokerage commissions. Such Shares were purchased with working capital (which may at any given time, include margin loans made by brokerage firms in the ordinary course of business) in open market purchases except as otherwise noted.

The aggregate purchase price of the 14,893 Shares held by Mr. Karpus and the Karpus Entities is approximately $110,186, excluding brokerage commissions. Such Shares were purchased with working capital (which may at any given time, include margin loans made by brokerage firms in the ordinary course of business) in open market purchases except as otherwise noted.

CUSIP NO. 56165R103

Item 5.

Interest in Securities of the Issuer.

Item 5(a)-(c) is hereby amended and restated to read as follows:

The aggregate percentage of Shares reported owned by each Reporting Person is based on 6,800,476 Shares outstanding, which is the total number of Shares outstanding as of January 31, 2018, as reported in the Issuer's Semi-Annual Report to Shareholders, filed with the U.S. Securities and Exchange Commission on March 29, 2018.

A.	Karpus Investment Management

(a)

As of July 30, 2018, Karpus directly beneficially owned 0 Shares, and as the investment adviser of the Accounts may be deemed to beneficially own the 489,053 Shares held in the Accounts.

Percentage: Approximately 7.19%

(b)

1. Sole power to vote or direct vote: 489,053

2. Shared power to vote or direct vote: 0

3. Sole power to dispose or direct the disposition: 489,053

4. Shared power to dispose or direct the disposition: 0

(c)

The transactions in the Shares by Karpus since the filing of the last Schedule 13D are set forth in Schedule B and incorporated herein by reference.

B.	George W. Karpus

(a)

As of July 30, 2018, George W. Karpus directly beneficially owned 34,983 Shares, and as the President and CEO of Karpus, may be deemed to beneficially own the 0 Shares owned by Karpus.

Percentage: Less than 1%

(b)

1. Sole power to vote or direct vote: 8,268

2. Shared power to vote or direct vote: 0

3. Sole power to dispose or direct the disposition: 8,268

4. Shared power to dispose or direct the disposition: 0

(c)

The transactions in the Shares by Mr. Karpus since the filing of the last Schedule 13D are set forth in Schedule B and incorporated herein by reference..

CUSIP NO. 56165R103

SIGNATURES

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

Dated: July 31, 2018

KARPUS MANAGEMENT, INC.

By:	/s/ Daniel L. Lippincott
	Name:	Daniel L. Lippincott, CFA
	Title:	Director of Investment Personnel and Sr. Tax-Sensitive Portfolio Manager

	/s/ George W. Karpus
	GEORGE W. KARPUS

CUSIP NO. 56165R103

SCHEDULE A

Executive Officers & Directors of Karpus Management, Inc., d/b/a Karpus Investment Management

Name	Position & Present Principal Occupation	Business Address	Shares Owned
George W. Karpus	President, CEO, and Chairman of the Board	183 Sully’s Trail, Pittsford, New York 14534	See Above
Kathleen Finnerty Crane	Chief Financial Officer and Chief Compliance Officer	183 Sully’s Trail, Pittsford, New York 14534	None
Dana R. Consler	Executive Vice President	183 Sully’s Trail, Pittsford, New York 14534	None
Thomas M. Duffy	Vice President	183 Sully’s Trail, Pittsford, New York 14534	None
Sharon L. Thornton	Senior Director of Investments	183 Sully’s Trail, Pittsford, New York 14534	None
Daniel L. Lippincott	Sr. Tax-Sensitive Manager and Director of Investment Personnel	183 Sully’s Trail, Pittsford, New York 14534	None

CUSIP NO. 56165R103

SCHEDULE B

Transactions in the Shares Since the filing of the last Schedule 13D

Nature of the Transaction

Securities

Purchased/(Sold)

Price Per

Share($)

Date of

Purchase / Sale

KARPUS MANAGEMENT, INC., D/B/A/ KARPUS INVESTMENT MANAGEMENT
(THROUGH THE ACCOUNTS)

Sale of Common Stock	(4,581)	$14.31	7/26/2018
Sale of Common Stock	(6,204)	$14.32	7/27/2018
Sale of Common Stock	(128,960)	$14.32	7/30/2018

MR. KARPUS AND THE KARPUS ENTITIES

Sale of Common Stock

(7,225)

$14.32

7/30/2018

MANAGED DURATION INVESTMENT GRADE MUNICIPAL FUND SC 13D/A