Checking Corporate Actions Before Trusting Split-Adjusted Price Data
Summary
The document examines a discrepancy in historical data for Brown-Forman Class A shares. A vendor reports a stock distribution around February 2018, while the adjusted series contains an apparent price jump and the investor cannot find a matching filing in the initial records searched. The discussion warns that corporate-action errors can distort quantitative research and trading results.
One reply attributes the vendor discrepancy to a restructure being applied twice in the data, and another recommends checking the company’s annual filing for the actual terms. That filing describes a stock dividend approved in January 2018, based on shares held as of February 7, with distribution later that month; it also distinguishes the event from an earlier split. The exchange illustrates why adjusted prices should be reconciled against issuer filings and why matching labels across data websites does not establish independent confirmation. It does not provide a general correction procedure or establish the complete provenance of every vendor’s records.
Key ideas
- Corporate-action mistakes can introduce artificial jumps into adjusted historical prices.
- Multiple websites may share the same underlying erroneous data source.
- Issuer filings can clarify the terms and dates of a stock dividend or split.
- Researchers should verify corporate actions before using adjusted prices in quantitative analysis.
Tags
Full text
# Verify the split history of BF.A # Verify the split history of BF.A https://finance.yahoo.com/quote/BF-A/history?period1=1517875200&period2=1518134400&interval=1d&filter=history&frequency=1d&includeAdjustedClose=true Yahoo Finance says BF-A has a 1339:1000 split event on Feb 07, 2018. However, the split-adjusted stock has a jump from Feb 06, 2018 to Feb 07, 2018. This doesn't seem to be right, as one should not expect such a big jump even after the adjustment for the split event. On EDGAR, I don't see any relevant document describing this split event. https://www.sec.gov/edgar/search/#/dateRange=custom&ciks=0000014693&entityName=BROWN%2520FORMAN%2520CORP%2520(BF-B%252C%2520BF-A)%2520(CIK%25200000014693)&startdt=2017-01-01&enddt=2017-03-01 Can I conclude that this split event did not exist? splithistory.com also shows the same split event. https://www.splithistory.com/?symbol=BF.A If both websites have the same error, the error must be from a common source. Does anybody know where the error came from? ## Answer by TraderPatrick (score 2) https://quant.stackexchange.com/a/70320 The source of the error in Yahoo Finance is CSI Data, who provide the data to Yahoo. This error is present in their product, Unfair Advantage. This issue is present in that they have accounted for this company restructure twice - once around the record date event, and once on the actual ex date. The reason for this is that this type of distribution is out-of-the-ordinary and they appear to lack quality control in this area. The impact of these sorts of errors are massive in quant trading - Garbage In, Garbage Out! ## Answer by Dimitri Vulis (score 1) https://quant.stackexchange.com/a/70316 What problem(s) are you trying to solve here? If you're trying to convince yourself that free data on the Internet is not fully trustworthy, then you have already succeded hundredfold. If you're trying to verify the details of Brown-Forman's 2018 split (more precisely, stock dividend), then start with their fy 2018 10K, fortunately recent enough to be free on Edgar: https://www.sec.gov/Archives/edgar/data/14693/000001469318000084/bfb-2018430x10kapril.htm > Note 10 Common Stock On May 26, 2016, our Board of Directors approved a two-for-one stock split for our Class A and Class B common stock, subject to stockholder approval of an amendment to our Restated Certificate of Incorporation. The stock split, which was effected as a stock dividend, resulted in the issuance of one new share of Class A common stock for each share of Class A common stock outstanding and one new share of Class B common stock for each share of Class B common stock outstanding. The new shares were distributed on August 18, 2016, to shareholders of record as of August 8, 2016. On January 23, 2018, our Board of Directors approved a stock split, effected in the form of a stock dividend. For every four shares of either Class A or Class B common stock held, shareholders of record as of the close of business on February 7, 2018, received one share of Class B common stock, with any fractional shares payable in cash. The additional shares and cash for fractional shares were distributed to stockholders on February 28, 2018.
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