Wellington Management group filed a Schedule 13G reporting shared beneficial ownership of 1,189,031 shares of Mercantile Bank Corporation common stock, representing 6.9% of the class as of 03/31/2026. The filing lists multiple Wellington entities and states these shares are owned of record by clients of Wellington investment advisers.
The cover responses show shared voting power and shared dispositive power across the named Wellington entities; signatures are dated 05/15/2026.
Positive
None.
Negative
None.
Insights
Wellington group reports a passive, >5% stake in MBWM held for advisory clients.
The filing identifies 1,189,031 shares and a 6.9% ownership figure as of 03/31/2026, with shared voting and dispositive power across Wellington entities. The schedule classifies the position as ownership on behalf of advisory clients rather than direct proprietary ownership.
Follow-up disclosure items to watch in subsequent filings include any amendment to percentage ownership or a change in voting/dispositive allocations among the listed entities.
Multiple Wellington affiliates are listed as holders, indicating layered ownership and adviser-client record ownership.
The schedule names Wellington Management Group LLP and several related entities and states the securities are owned of record by clients of the Wellington Investment Advisers. Item 6 clarifies no single client is known to hold more than 5% separately.
Investor-facing implications are administrative: the position reflects advisory-held assets rather than an operating-control stake.
Key Figures
Filing date (as of):03/31/2026Shares beneficially owned:1,189,031 sharesPercent of class:6.9%+1 more
4 metrics
Filing date (as of)03/31/2026Ownership measurement date
"Wellington Management group filed a Schedule 13G reporting shared beneficial"
A Schedule 13G is a formal document that investors file with the government when they acquire a large ownership stake in a company, usually for investment purposes rather than control. It helps keep the public informed about who owns significant parts of a company's shares, which can influence how the company is managed and how investors make decisions. Filing this schedule is important for transparency and understanding the ownership landscape of publicly traded companies.
Shared Dispositive Powerfinancial
"Shared Dispositive Power 1,189,031.00"
Investment Adviser (IA)regulatory
"Wellington Management Company LLP - IA Wellington Management Canada LLC - IA"
An investment adviser (IA) is a person or firm that provides personalized guidance on buying, selling, or holding investments and often manages client portfolios for a fee. Investors should care because an IA has a legal duty to act in the client's best interest—think of them as a navigator who plans and steers your financial journey—so their advice, fee structure and potential conflicts can directly affect returns and financial risk.
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
Mercantile Bank Corporation
(Name of Issuer)
Common Stock
(Title of Class of Securities)
587376104
(CUSIP Number)
03/31/2026
(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)
schemaVersion:
SCHEDULE 13G
CUSIP Number(s):
587376104
1
Names of Reporting Persons
Wellington Management Group LLP
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
MASSACHUSETTS
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
1,040,984.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,189,031.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,189,031.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
6.9 %
12
Type of Reporting Person (See Instructions)
HC
SCHEDULE 13G
CUSIP Number(s):
587376104
1
Names of Reporting Persons
Wellington Group Holdings LLP
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
0.00
6
Shared Voting Power
1,040,984.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,189,031.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,189,031.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
6.9 %
12
Type of Reporting Person (See Instructions)
HC
SCHEDULE 13G
CUSIP Number(s):
587376104
1
Names of Reporting Persons
Wellington Investment Advisors Holdings LLP
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
0.00
6
Shared Voting Power
1,040,984.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,189,031.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,189,031.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
6.9 %
12
Type of Reporting Person (See Instructions)
HC
SCHEDULE 13G
CUSIP Number(s):
587376104
1
Names of Reporting Persons
Wellington Management Company LLP
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
0.00
6
Shared Voting Power
1,030,352.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,128,843.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,189,031.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
6.5 %
12
Type of Reporting Person (See Instructions)
IA
SCHEDULE 13G
Item 1.
(a)
Name of issuer:
Mercantile Bank Corporation
(b)
Address of issuer's principal executive offices:
310 Leonard Street Northwest, Grand Rapids MI
Item 2.
(a)
Name of person filing:
Wellington Management Group LLP
Wellington Group Holdings LLP
Wellington Investment Advisors Holdings LLP
Wellington Management Company LLP
(b)
Address or principal business office or, if none, residence:
c/o Wellington Management Company LLP, 280 Congress Street, Boston MA 02210
(c)
Citizenship:
Wellington Management Group LLP - Massachusetts
Wellington Group Holdings LLP - Delaware
Wellington Investment Advisors Holdings LLP - Delaware
Wellington Management Company LLP - Delaware
(d)
Title of class of securities:
Common Stock
(e)
CUSIP Number(s):
587376104
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)
A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J),
please specify the type of institution:
(k)
Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.
Ownership
(a)
Amount beneficially owned:
See the responses to Item 9 on the attached cover pages.
(b)
Percent of class:
6.88 %
(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:
See the responses to Item 6 on the attached cover pages.
(iii) Sole power to dispose or to direct the disposition of:
0
(iv) Shared power to dispose or to direct the disposition of:
See the responses to Item 8 on the attached cover pages.
Item 5.
Ownership of 5 Percent or Less of a Class.
Not Applicable
Item 6.
Ownership of more than 5 Percent on Behalf of Another Person.
If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required.
The securities as to which this Schedule is filed are owned of record by clients of one or more investment advisers identified in Item 7 directly or indirectly owned by Wellington Management Group LLP. Those clients have the right to receive, or the power to direct the receipt of, dividends from, or the proceeds from the sale of, such securities. No such client is known to have such right or power with respect to more than five percent of this class of securities, except as follows:
Not Applicable.
Item 7.
Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
If a parent holding company has filed this schedule, pursuant to Rule 13d-1(b)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the identity and the Item 3 classification of the relevant subsidiary. If a parent holding company has filed this schedule pursuant to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating the identification of the relevant subsidiary.
Pursuant to the instructions in Item 7 of Schedule 13G, the following lists the identity and Item 3 classification of each relevant entity that beneficially owns shares of the security class being reported on this Schedule 13G.
Wellington Group Holdings LLP - HC
Wellington Investment Advisors LLP - HC
Wellington Management Global Holdings, Ltd. - HC
One or more of the following investment advisers (the "Wellington Investment Advisers"):
Wellington Management Company LLP - IA
Wellington Management Canada LLC - IA
Wellington Management Singapore Pte Ltd - IA
Wellington Management Hong Kong Ltd - IA
Wellington Management International Ltd - IA
Wellington Management Japan Pte Ltd - IA
Wellington Management Australia Pty Ltd - IA
The securities as to which this Schedule is filed by Wellington Management Group LLP, as parent holding company of certain holding companies and the Wellington Investment Advisers, are owned of record by clients of the Wellington Investment Advisers. Wellington Investment Advisors Holdings LLP controls directly, or indirectly through Wellington Management Global Holdings, Ltd., the Wellington Investment Advisers. Wellington Investment Advisors Holdings LLP is owned by Wellington Group Holdings LLP. Wellington Group Holdings LLP is owned by Wellington Management Group LLP.
Item 8.
Identification and Classification of Members of the Group.
Not Applicable
Item 9.
Notice of Dissolution of Group.
Not Applicable
Item 10.
Certifications:
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, other than activities solely in connection with a nomination under ?? 240.14a-11.
SIGNATURE
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.
What stake does Wellington Management report in Mercantile Bank (MBWM)?
The filing reports shared beneficial ownership of 1,189,031 shares, representing 6.9% of Mercantile Bank Corporation common stock as of 03/31/2026. The shares are reported as held of record for advisory clients of Wellington entities.
Which Wellington entities are named on the Schedule 13G for MBWM?
The Schedule 13G lists Wellington Management Group LLP, Wellington Group Holdings LLP, Wellington Investment Advisors Holdings LLP, and Wellington Management Company LLP as reporting persons, with related Wellington investment adviser entities identified in Item 7.
Does the filing indicate Wellington has sole voting or dispositive power over MBWM shares?
No sole powers are reported. The filing shows 0 sole voting and dispositive power and discloses shared voting and shared dispositive power across the named Wellington entities for the reported 1,189,031 shares.
Are these Wellington-held MBWM shares owned directly by Wellington or by clients?
The filing states the securities are owned of record by clients of the Wellington Investment Advisers and held on their behalf. It further states no single client is known to own more than 5% of the class separately.
