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Table of Contents U.S. SECURITIES AND EXCHANGE COMMISSION Washington , DC 20549 FORM 10 - Q × QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30 , 2021 □ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Michigan Commission File No. 000-26719 MERCANTILE BANK CORPORATION ( Exact name of registrant as specified in its charter ) ( State or other jurisdiction of incorporation or organization ) 38-3360865 ( IRS Employer Identification No. ) 310 Leonard Street , NW , Grand Rapids , MI 49504 ( Address of principal executive offices ) ( Zip Code ) ( 616 ) 406-3000 ( Registrant's telephone number , including area code ) Indicate by check mark whether the registrant ( 1 ) has filed all reports required to be filed by Section 13 or 15 ( d ) of the Securities Exchange Act of 1934 during the preceding 12 months ( or for such shorter period that the registrant was required to file such reports ) , and ( 2 ) has been subject to such filing requirements for the past 90 days . Yes ☑ No □ Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S - T during the preceding 12 months ( or for such shorter period that the registrant was required to submit such files ) . Yes ☑ No □ Indicate by check mark whether the registrant is a large accelerated filer , an accelerated filer , a non - accelerated filer , a smaller reporting company , or an emerging growth company . See the definitions of “ large accelerated filer , ” “ accelerated filer , ” “ smaller reporting company , ” and “ emerging growth company ” in Rule 12b - 2 of the Exchange Act . Non - accelerated filer ☐ Large accelerated filer ☐ Emerging growth company □ Securities registered pursuant to Section 12 ( b ) of the Exchange Act : Accelerated filer ☑ Smaller reporting company □ Title of each class Common Stock Trading Symbol ( s ) MBWM Name of each exchange on which registered The Nasdaq Stock Market LLC If an emerging growth company , indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13 ( a ) of the Exchange Act . Yes □ No □ Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Exchange Act ) . Yes ☐ No ☑ At October 29 , 2021 , there were 15,670,645 shares of common stock outstanding .