Zitat aus dem in # 876 verlinkten "Handelszeitungs"-Artikel:
"Von den Rückschlägen des «Black Thursday» 1929 (minus 15 Prozent beim Dow Jones), «Black Monday» 1987 (minus 20 Prozent) oder des Nikkei-Crash 2007 (minus 11 Prozent) sind wir also noch ein ganzes Stück entfernt."
A.L.: In USA gibt es seit dem 1987-Crash automatische Handelsaussetzungen ("trading curbs"), die greifen, sobald ein großer Index um einen bestimmten Prozentbetrag gesackt ist. Seit 2013 gilt: Tritt ein Index-Preisverfall kurz nach Handelsbeginn auf, wird bereits bei -7 % die Notbremse gezogen. Dann gibt es einen 15-Minütigen Handelsstopp. Level 2 erlaubt Rücksetzer bis -13 %. Level 3 greift ab -20 % - und setzt den Handel für den ganzen Tag aus. Ein Rücksetzer wie 1987 (-22 % an einem Tag, die Angabe von 20 % in der HZ ist zu niedrig) wäre heute also schon rein technisch nicht mehr möglich.
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Trading curb (wiki)
en.wikipedia.org/wiki/Trading_curb
A trading curb, sometimes referred to as a circuit breaker, is a financial regulatory instrument that is in place to prevent stock market crashes from occurring. Since their inception, circuit breakers have been modified to prevent both speculative gains and dramatic losses within a small time frame. As a result of being triggered, circuit breakers either stop trading for a small amount of time or close trading early in order to allow accurate information to flow amongst market makers and for institutional traders to assess their positions and make rational decisions.
On the New York Stock Exchange (NYSE), one type of trading curb is referred to as a "circuit breaker". These limits were put in place after Black Monday in 1987 in order to reduce market volatility and massive panic sell-offs, giving traders time to reconsider their transactions....
The most recently updated amendment of rule 80B went into effect on April 8, 2013, and has three tiers of thresholds that have different protocols for halting trading and closing the markets.
At the start of each day, the NYSE sets three circuit breaker levels at levels of 7% (Level 1), 13% (Level 2) and 20% (Level 3). These thresholds are the percentage drops in value that the S&P 500 Index would have to suffer in order for a trading halt to occur. Base price levels for which these thresholds will be applied are calculated daily based on the preceding trading day’s closing value of the S&P 500. Depending on the point drop that happens and the time of day when it happens, different actions occur automatically: Level 1 and Level 2 declines result in a 15-minute trading halt unless they occur after 3:25pm, when no trading halts apply. A Level 3 decline results in trading being suspended for the remainder of the day.[1]
Circuit breakers are also in effect on the Chicago Mercantile Exchange (CME) and all subsidiary exchanges where the same thresholds that the NYSE has are applied to equity index futures trading. However, there is a CME specific price limit that prevents 5% increases and decreases in price during after hours trading.[2] Base prices for which the percentage thresholds are applied are derived from the weighted average price on the future during the preceding trading day's last thirty seconds of trading. Price limits for equity index and foreign exchange futures are posted on the CME website at the close of each trading session.[3]