UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 10-Q (Mark One) ý Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the quarterly period ended September 30, 2020 or ¨ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the transition period from to Commission File Number: 001-34146 CLEARWATER PAPER CORPORATION (509) 344-5900 (Registrant's telephone number, including area code) ____________________ ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 10-Q (Mark One) ý Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the quarterly period ended June 30, 2020 or ¨ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the transition period from to Commission File Number: 001-34146 CLEARWATER PAPER CORPORATION (Exact name of registrant as specified in its charter) DE 20-3594554 (State or other jurisdic ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 10-Q (Mark One) Title of each class Trading Symbol(s) Name of each exchange on which registered ý Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the quarterly period ended March 31, 2020 or ¨ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the transition period from to Commission File Number: 001-34146 CLEARWATER PAPER CORPORATION (Exact name ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K (Mark One) ý ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2019 OR ¨ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Delaware 20-3594554 (State or other jurisdiction of incorporation or organization) (IRS Employer Identification No.) 601 W. Riverside Avenue, Suite 1100 Spokane ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 10-Q (Mark One) ý Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the quarterly period ended September 30, 2019 or ¨ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 | --- | --- | |-------------------------------------------------------------------------------|------------------------------------------| | For the transition period from | to | | Comm ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 10-Q (Mark One) ý Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the quarterly period ended June 30, 2019 or ¨ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 | --- | --- | |-------------------------------------------------------------------------------|------------------------------------------| | For the transition period from | to | | Commissio ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 10-Q (Mark One) ý Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the quarterly period ended March 31, 2019 or ¨ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 | --- | --- | |-------------------------------------------------------------------------------|------------------------------------------| | For the transition period from | to | | Commissi ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 Form 10-K (Mark One) ý ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2018 OR ¨ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-34146 CLEARWATER PAPER CORPORATION (Exact name of registrant as specified in its charter) Delaware 20-3594554 (State or other jurisd ...