PACKAGING CORP OF AMERICA 10-Q

Item 2. UNREGISTERED SALES OF EQUI TY SECURITIES AND USE OF PROCEEDS The following table presents information related to our repurchases of common stock made under repurchase plans authorized by PCA's Board of Directors, and shares withheld to cover taxes on vesting of equity awards, during the three months ended June 30, 2022: Issuer Purchases of Equity Securities Period Total Number of Shares Purchased (a) Average Price Paid Per Share Total Number of Shares Purchased as Part of Publicly Announced Plans or Programs Approximate Dollar Value of Shares That May Yet Be Purchased Under the Plans or Programs (in millions) April 1-30, 2022 154 $ 155.76 — $ 1,000.0 May 1-31, 2022 230 156.23 — 1,000.0 June 1-30, 2022 65,429 141.69 — 1,000.0 Total 65,813 $ 141.77 — $ 1,000.0 (a) All shares were withheld from employees to cover income and payroll taxes on equity awards that vested during the period. Item 3. DEFAULTS UPO N SENIOR SECURITIES None. Item 4. MINE SAF ETY DISCLOSURES Not applicable. Item 5. OTHE R INFORMATION None. 28 Item 6. EXHIBITS Exhibit Number Description 31.1 Certification of Chief Executive Officer, as Adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. † 31.2 Certification of Chief Financial Officer, as Adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. † 32 Certification of Chief Executive Officer and Chief Financial Officer Pursuant to 18 U.S.C. §1350, as Adopted Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002. † 101.INS Inline XBRL Instance Document – the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document. † 101.SCH Inline XBRL Taxonomy Extension Schema Document. † 101.CAL Inline XBRL Taxonomy Extension Calculation Linkbase Document. † 101.DEF Inline XBRL Taxonomy Extension Definition Linkbase Document. † 101.LAB Inline XBRL Taxonomy Extension Label Linkbase Document. † 101.PRE Inline XBRL Taxonomy Extension Presentation Linkbase Document. † 104 Cover Page Interactive Data File (formatted as inline XBRL and contained in Exhibit 101). † † Filed herewith. 29 SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized. Packaging Corporation of America /s/ PAMELA A. BARNES Pamela A. Barnes Senior Vice President, Finance and Controller Date: August 4, 2022 30