Corporate Governance Board of Directors Management Team Sustainability Financials Quarterly Results SEC Filings Stock Senior Notes Common Stock Warrants Tax Documents Dividends Press Releases Events and Presentations Company Reports Annual Reports Sustainability Reports Climate-Related Analysis Reports Contact SEC Filings Home / Investors / Financials / SEC Filings NASDAQ: CHKOTCPK: CHKAQYearCalendar Year 2021Calendar Year 2020ViewAll FilingsQuarterly FilingsCurrent FilingsRegistration StatementsSection 16OtherFormDescriptionDateFormatCERTCERTFeb 9, 2021Open CERT in HTML.Open CERT in DOC file.Open CERT in PDF file.Open CERT in XLS file.SC 13G/AAmendment to a previously filed SC 13GFeb 2, 2021Open Amendment to a previously filed SC 13G in HTML.Open Amendment to a previously filed SC 13G in DOC file.Open Amendment to a previously filed SC 13G in PDF file.Open Amendment to a previously filed SC 13G in XLS file.