DAX daily (Yahoo ^GDAXI), file gdaxi_daily.csv: 9830 rows 1987-12-30 .. 2026-11-11; 168 stamps with a null close left out by rdx_parse.js 1. Dates and the cut ok first day - 1987-12-30 ok the cut: last kept day is 2026-10-20 - last kept 2026-10-20; 9814 days kept, 16 later days not used 2. Order, weekends, values ok dates strictly increasing (no duplicate or backward date) ok no Saturday or Sunday ok every close present and positive ok adjusted close equal to the close (an index: no adjustment) - 0 days differ ok open, high, low consistent with the close where present - 0 days bars with open = high = low = close (no intraday prices) or no open, by year: 1987 1/1, 1988 251/251, 1989 250/250, 1990 248/248, 1991 248/248, 1992 251/251, 1993 240/252, 1997 1/250 first year with real opens on at least 95% of days: 1994 3. Trading days per year; missing weekdays classified days per year: 1987 1, 1988 251, 1989 250, 1990 248, 1991 248, 1992 251, 1993 252, 1994 252, 1995 251, 1996 250, 1997 250, 1998 251, 1999 253, 2000 254, 2001 253, 2002 253, 2003 253, 2004 257, 2005 257, 2006 255, 2007 252, 2008 254, 2009 254, 2010 256, 2011 256, 2012 253, 2013 252, 2014 252, 2015 253, 2016 255, 2017 252, 2018 251, 2019 251, 2020 254, 2021 255, 2022 257, 2023 255, 2024 254, 2025 253, 2026 205 ok every full year has 240 to 258 trading days missing weekdays (311, of which 168 appear in Yahoo as stamps with a null close): Xetra holiday (current list) 242; older holiday: Ascension 12; older holiday: Whit Monday 20; older holiday: Corpus Christi 11; older holiday: 17 June (until 1990) 1; older holiday: Day of Prayer and Repentance (until 1994) 7; GAP 3; older holiday: German Unity Day (3 October) 15 FLAG missing weekdays that are no known holiday (gaps) - 3: 1988-12-30 1989-12-29 2017-10-31 days present on a date that is a holiday in the lists above (84): 1997-05-29 (older holiday: Corpus Christi), 2000-06-01 (older holiday: Ascension), 2000-06-12 (older holiday: Whit Monday), 2000-06-22 (older holiday: Corpus Christi), 2001-05-24 (older holiday: Ascension), 2001-06-04 (older holiday: Whit Monday), 2001-06-14 (older holiday: Corpus Christi), 2001-10-03 (older holiday: German Unity Day (3 October)), 2002-05-09 (older holiday: Ascension), 2002-05-20 (older holiday: Whit Monday), 2002-05-30 (older holiday: Corpus Christi), 2002-10-03 (older holiday: German Unity Day (3 October)), 2003-05-29 (older holiday: Ascension), 2003-06-09 (older holiday: Whit Monday), 2003-06-19 (older holiday: Corpus Christi), 2003-10-03 (older holiday: German Unity Day (3 October)), 2004-05-20 (older holiday: Ascension), 2004-05-31 (older holiday: Whit Monday), 2004-06-10 (older holiday: Corpus Christi), 2005-05-05 (older holiday: Ascension), 2005-05-16 (older holiday: Whit Monday), 2005-05-26 (older holiday: Corpus Christi), 2005-10-03 (older holiday: German Unity Day (3 October)), 2006-05-25 (older holiday: Ascension), 2006-06-05 (older holiday: Whit Monday), 2006-06-15 (older holiday: Corpus Christi), 2006-10-03 (older holiday: German Unity Day (3 October)), 2007-05-17 (older holiday: Ascension), 2007-06-07 (older holiday: Corpus Christi), 2007-10-03 (older holiday: German Unity Day (3 October)), 2008-05-12 (older holiday: Whit Monday), 2008-05-22 (older holiday: Corpus Christi), 2008-10-03 (older holiday: German Unity Day (3 October)), 2009-05-21 (older holiday: Ascension), 2009-06-01 (older holiday: Whit Monday), 2009-06-11 (older holiday: Corpus Christi), 2010-05-13 (older holiday: Ascension), 2010-05-24 (older holiday: Whit Monday), 2010-06-03 (older holiday: Corpus Christi), 2011-06-02 (older holiday: Ascension), 2011-06-13 (older holiday: Whit Monday), 2011-06-23 (older holiday: Corpus Christi), 2012-05-17 (older holiday: Ascension), 2012-05-28 (older holiday: Whit Monday), 2012-06-07 (older holiday: Corpus Christi), 2013-05-09 (older holiday: Ascension), 2013-05-20 (older holiday: Whit Monday), 2013-05-30 (older holiday: Corpus Christi), 2014-05-29 (older holiday: Ascension), 2014-06-09 (older holiday: Whit Monday), 2014-06-19 (older holiday: Corpus Christi), 2015-05-14 (older holiday: Ascension), 2015-06-04 (older holiday: Corpus Christi), 2016-05-05 (older holiday: Ascension), 2016-05-26 (older holiday: Corpus Christi), 2017-05-25 (older holiday: Ascension), 2017-06-15 (older holiday: Corpus Christi), 2018-05-10 (older holiday: Ascension), 2018-05-31 (older holiday: Corpus Christi), 2019-05-30 (older holiday: Ascension), 2019-06-20 (older holiday: Corpus Christi), 2020-05-21 (older holiday: Ascension), 2020-06-11 (older holiday: Corpus Christi), 2021-05-13 (older holiday: Ascension), 2021-06-03 (older holiday: Corpus Christi), 2022-05-26 (older holiday: Ascension), 2022-06-06 (older holiday: Whit Monday), 2022-06-16 (older holiday: Corpus Christi), 2022-10-03 (older holiday: German Unity Day (3 October)), 2023-05-18 (older holiday: Ascension), 2023-05-29 (older holiday: Whit Monday), 2023-06-08 (older holiday: Corpus Christi), 2023-10-03 (older holiday: German Unity Day (3 October)), 2024-05-09 (older holiday: Ascension), 2024-05-20 (older holiday: Whit Monday), 2024-05-30 (older holiday: Corpus Christi), 2024-10-03 (older holiday: German Unity Day (3 October)), 2025-05-29 (older holiday: Ascension), 2025-06-09 (older holiday: Whit Monday), 2025-06-19 (older holiday: Corpus Christi), 2025-10-03 (older holiday: German Unity Day (3 October)), 2026-05-14 (older holiday: Ascension), 2026-05-25 (older holiday: Whit Monday), 2026-06-04 (older holiday: Corpus Christi) calendar jumps of more than 4 days between two rows: 1987-12-30 -> 1988-01-04, 1988-03-31 -> 1988-04-05, 1989-03-23 -> 1989-03-28, 1989-12-22 -> 1989-12-27, 1989-12-28 -> 1990-01-02, 1990-04-12 -> 1990-04-17, 1990-12-21 -> 1990-12-27, 1990-12-28 -> 1991-01-02, 1991-03-28 -> 1991-04-02, 1992-04-16 -> 1992-04-21, 1992-12-23 -> 1992-12-28, 1992-12-30 -> 1993-01-04, 1993-04-08 -> 1993-04-13, 1994-03-31 -> 1994-04-05, 1995-04-13 -> 1995-04-18, 1995-12-22 -> 1995-12-27, 1996-04-04 -> 1996-04-09, 1997-03-27 -> 1997-04-01, 1997-12-23 -> 1997-12-29, 1998-04-09 -> 1998-04-14, 1998-12-23 -> 1998-12-28, 1998-12-30 -> 1999-01-04, 1999-04-01 -> 1999-04-06, 2000-04-20 -> 2000-04-25, 2000-12-22 -> 2000-12-27, 2001-04-12 -> 2001-04-17, 2001-12-21 -> 2001-12-27, 2001-12-28 -> 2002-01-02, 2002-03-28 -> 2002-04-02, 2003-04-17 -> 2003-04-22, 2003-12-23 -> 2003-12-29, 2004-04-08 -> 2004-04-13, 2005-03-24 -> 2005-03-29, 2006-04-13 -> 2006-04-18, 2006-12-22 -> 2006-12-27, 2007-04-05 -> 2007-04-10, 2007-12-21 -> 2007-12-27, 2007-12-28 -> 2008-01-02, 2008-03-20 -> 2008-03-25, 2008-12-23 -> 2008-12-29, 2009-04-09 -> 2009-04-14, 2009-12-23 -> 2009-12-28, 2009-12-30 -> 2010-01-04, 2010-04-01 -> 2010-04-06, 2011-04-21 -> 2011-04-26, 2012-04-05 -> 2012-04-10, 2012-12-21 -> 2012-12-27, 2012-12-28 -> 2013-01-02, 2013-03-28 -> 2013-04-02, 2014-04-17 -> 2014-04-22, 2014-12-23 -> 2014-12-29, 2015-04-02 -> 2015-04-07, 2015-12-23 -> 2015-12-28, 2015-12-30 -> 2016-01-04, 2016-03-24 -> 2016-03-29, 2017-04-13 -> 2017-04-18, 2017-12-22 -> 2017-12-27, 2018-03-29 -> 2018-04-03, 2018-12-21 -> 2018-12-27, 2018-12-28 -> 2019-01-02, 2019-04-18 -> 2019-04-23, 2020-04-09 -> 2020-04-14, 2020-12-23 -> 2020-12-28, 2020-12-30 -> 2021-01-04, 2021-04-01 -> 2021-04-06, 2022-04-14 -> 2022-04-19, 2023-04-06 -> 2023-04-11, 2023-12-22 -> 2023-12-27, 2024-03-28 -> 2024-04-02, 2025-04-17 -> 2025-04-22, 2025-12-23 -> 2025-12-29, 2026-04-02 -> 2026-04-07 4. Stale quotes ok no run of 3 or more identical closes pairs of consecutive identical closes: 0 5. Daily moves above 8% (close to close, consecutive rows) 1989-10-16 -13.14% (from 1989-10-13) 1991-08-19 -9.18% (from 1991-08-16) 2001-09-11 -8.49% (from 2001-09-10) 2008-10-13 +11.4% (from 2008-10-10) 2008-10-28 +11.28% (from 2008-10-27) 2008-11-24 +10.34% (from 2008-11-21) 2020-03-12 -12.24% (from 2020-03-11) 2020-03-24 +10.98% (from 2020-03-23) ok no daily move above 15% - largest 13.14% 6. Cross-check against the HistData DAX 1-minute file (last cash-session minute, up to 17:29 Frankfurt) HistData loaded in 30 s; Yahoo days in the HistData range that HistData may hold: 3098; days with a HistData last minute at 17:20 or later: 3088 level difference HistData / Yahoo: median |d| 0.071%, 95th pct 0.293%, max 0.936%; mean d 0.023% correlation of daily changes on 3078 consecutive common days: 0.9917 ok no common day differs by more than 1% - 0 7. Clock: not applicable (a daily series with dates only, not an MT4 file); Yahoo stamps are 09:00 Frankfurt, used only for the date. 1 check(s) flagged, to be read by hand before the freeze