Non succedeva dal marzo 2009, le borse azionarie americane, prima dell’apertura hanno dichiarato la cosidetta rule 48 (regola 48):
Rule 48
(a) In the event that extremely high market volatility is likely to have a Floor-wide impact on the ability of [Designated Market Makers] to arrange for the fair and orderly opening, reopening following a market-wide halt of trading at the Exchange, or closing of trading at the Exchange and that absent relief, the operation of the Exchange is likely to be impaired, a qualified Exchange officer may declare an extreme market volatility condition with respect to trading on or through the facilities of the Exchange.
(b) In the event that an extreme market volatility condition is declared with respect to trading on or through the facilities of the Exchange, a qualified Exchange officer shall be empowered to temporarily suspend at the opening of trading or reopening of trading following a market-wide trading halt: (i) the need for prior Floor Official or prior NYSE Floor operations approval to open or reopen a security at the Exchange (Rules 123D(1) and 79A.30); and/or (ii) applicable requirements to make pre-opening indications in a security (Rules 15 and 123D(1)).
In poche parole i market maker su Nyse e Amex oggi potranno fermare temporaneamente gli scambi “
a discrezione” di un ufficiale di borsa (Exchange Officer). In pratica i mercati possono essere sospesi in qualsiasi momento anche prima dei blocchi automatici.
La regola 48 è stata introdotta nel 2006 e uasata raramente, perchè possa essere usata deve essere dichiarata prima dell’inizio delle contrattazioni ufficiali.
E’ ovvio che solo in situazioni gravissime essa viene presa in considerazione. Ecco appunto, situazioni gravissime.