Oil Price Volatility and Asset Write-Downs

All accounting data come from XBRL-tagged 10-K and 10-Q filings submitted to the SEC, obtained through three public channels. (i) For filings made between 2009 and 30 September 2020, the study uses a filing-level extraction of all XBRL financial statement facts published by SECDatabase.com as a public Amazon S3 data set (release 20200930). (ii) For impairments and accounting methods after 2020, the study uses the SEC’s own XBRL “frames” application programming interface (data.sec.gov), which returns, for one XBRL element and one calendar period, the most recently filed value reported by every registrant. Quarterly frames (three-month values) and annual frames were retrieved for 2020–2025. (iii) For annual total assets, total liabilities and net income after 2020, the study uses a derived data set that compiles each filer’s annual fundamentals from the SEC’s companyfacts records (github.com/loosygoosie/sec-dataset); because the values come from those records, they can be checked against data.sec.gov. Where the sources overlap, the values were compared: for the first two quarters of 2020, 28 of 35 and 27 of 31 firm-level impairment values agree exactly between sources (i) and (ii); the differences arise because several filers corrected their original 10-Q tags in later filings, which the frames reflect.