"Worst Week Since 2008"? Depends on the Ruler.

Описание: "Worst week since 2008." "Biggest point drop in history." Market headlines often measure in index points — and points inflate as an index rises. We measured real US market moves three ways: in points, in percent, and scaled by how volatile the market already was (a z-score). In the week to 21 Dec 2018, the Dow's fall really was its worst since October 2008, in points and in percent. The S&P 500's fall that same week was the worst since 2008 only in points; in percent it was the worst since August 2011.

Using FRED's free S&P 500 and Dow series (October 2016 to December 2025), we ranked every day and every week. All 20 of the largest one-day S&P point drops came in 2020 or later. Black Monday 1987 fell 20.5% but lost fewer than 70 points; more than 100 days in this decade alone lost more. The Dow's 19 thousand-point down days (2018–2025) ranged from a 2.5% to a 12.9% fall. The December 2018 week ranks 5th of 480 weeks by percent, but only 13th by points.

Data frozen at 31 Dec 2025. Limits of the method are covered in the video (10:59).

Chapters
00:00 "Worst week since 2008": by what ruler?
00:37 What actually happened: one week, two indices
03:32 Points against percent: the yardstick
06:10 The volatility ruler: how surprising was it?
09:47 Look-alikes: other "worst since" weeks
10:59 What this does not tell us
12:29 Verdict

Method (our calculation)
Daily change = close ÷ previous close − 1. Weekly change = Friday-to-Friday closes. Volatility-scaled move = % change ÷ standard deviation of daily changes over the previous 252 trading days. All ranks use FRED's SP500 and DJIA series only: daily and weekly ranks Oct 2016 – Dec 2025; volatility scores Oct 2017 – Dec 2025. Older figures are published numbers from the outlets listed below. Ranks are our calculation, not official statistics. Raw index price files are not redistributed (S&P Dow Jones Indices licence).

Sources
FRED, S&P 500 (SP500) and Dow Jones Industrial Average (DJIA), S&P Dow Jones Indices: https://fred.stlouisfed.org/series/SP500 · https://fred.stlouisfed.org/series/DJIA
UPI, 21 Dec 2018: https://www.upi.com/Top_News/US/2018/...
Schaeffer's Investment Research, 21 Dec 2018: https://www.schaeffersresearch.com/co...
NPR, 5 Feb 2018: https://www.npr.org/sections/thetwo-w...
Marketplace, 5 Feb 2018: https://www.marketplace.org/story/201...
AP via Christian Science Monitor, 5 Feb 2018: https://www.csmonitor.com/USA/2018/02...
Baltimore Sun, 14 Oct 2008: https://www.baltimoresun.com/2008/10/...
Forbes, 10 Oct 2008: https://www.forbes.com/2008/10/10/win...
CBS News, 28 Mar 2013 (S&P record 1,565.15): https://www.cbsnews.com/news/sp-500-s...
Reuters via Fortune, 22 Nov 2016: https://fortune.com/2016/11/22/donald...
Times of Israel (AP), 28 Feb 2020: https://www.timesofisrael.com/wall-st...
Al Jazeera, 20 Mar 2020: https://www.aljazeera.com/economy/202...
PBS NewsHour, 4 Apr 2025: https://www.pbs.org/newshour/politics...
Washington Post archive, "The Dow Hits 1000": https://www.washingtonpost.com/archiv...
Federal Reserve History, "Stock Market Crash of 1987": https://www.federalreservehistory.org...
CBS News/AP, 18 Oct 2017 (S&P on Black Monday): https://www.cbsnews.com/news/black-mo...
Yardeni, Predicting the Markets, Appendix 15.4 (S&P data): https://www.yardenibook.com/pub/15.4a...
S&P Dow Jones Indices, Dow Jones Industrial Average: https://www.spglobal.com/spdji/en/ind...

Disclaimer
The Measured Market is an educational channel. Nothing here is investment, tax or legal advice, a recommendation to buy or sell any security, or a forecast. We describe what historical data shows; history does not predict future returns. We are not registered with SEBI, the SEC or any regulator as an investment adviser or research analyst. Narration is produced with a synthetic (AI) voice; research, analysis, charts and script are by The Measured Market team. Data sources and method: listed above in this description. We will never contact you on WhatsApp/Telegram/DMs offering advice or "tips".

Corrections: errors found after publishing are logged in the pinned comment, with timestamps.