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UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON , D.C. 20549 Form 10 - K ( Mark One ) ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31 , 2020 TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from OR Commission file number 1-1070 ◆ lin ™ Virginia ( State or other jurisdiction of incorporation or organization ) 190 Carondelet Plaza , Suite 1530 , Clayton , MO ( Address of principal executive offices ) OLIN CORPORATION ( Exact name of registrant as specified in its charter ) to Securities registered pursuant to Section 12 ( b ) of the Act : 13-1872319 ( I.R.S. Employer Identification No. ) Registrant's telephone number , including area code : ( 314 ) 480-1400 63105 ( Zip code ) Title of each class : Trading symbol : OLN Common Stock , $ 1.00 par value per share Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . Yes No Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15 ( d ) of the Act . Yes No 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 Name of each exchange on which registered : New York Stock Exchange Document Proxy Statement relating to Olin's Annual Meeting of Shareholders to be held in 2021 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 ( § 232.405 of this chapter ) 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 . Large accelerated filer > Accelerated filer Non - accelerated filer Smaller reporting company Emerging growth company 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 . Indicate by check mark whether the registrant has filed a report on and attestation to its management's assessment of the effectiveness of its internal control over financial reporting under Section 404 ( b ) of the Sarbanes - Oxley Act ( 15 U.S.C. 7262 ( b ) ) by the registered public accounting firm that prepared or issued its audit report . » Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Exchange Act ) . Yes No As of June 30 , 2020 , the aggregate market value of registrant's common stock , $ 1.00 par value per share , held by non - affiliates of registrant was approximately $ 1,805,210,520 based on the closing sale price as reported on the New York Stock Exchange . As of January 31 , 2021 , 158,368,176 shares of the registrant's common stock were outstanding . DOCUMENTS INCORPORATED BY REFERENCE Portions of the following document are incorporated by reference in this Form 10 - K as indicated herein : Part of 10 - K into which incorporated Part III