The major issue that should concern most day traders is the rollout of Rule 201 (Alternative Uptick Rule). This will allow for a short sale-related circuit breaker that upon being hit would impose a condition for the pricing of equities short sold. All exchanges will not allow for the execution or show of short sale orders at a price that is less than or equal to the current national best bid should the stockâs price decline by 10% or more from the previous dayâs closing price at the end of regular trading hours on the previous day it traded. Thus if a stock is 11.35 bid to 11.40 offer and one wishes to short, one would only be able to do so at 11.36 if the stock was down 10% or more that day. The duration of the restriction will be through the close of trading on the next trading day thus if a stock declined 10% or more on a Monday morning, the restriction would be in effect until Tuesdayâs close. Furthermore, if a stock is halted intra-day, any short sale orders would be executed only one price tick above the open. Itâs also worth noting that it is very ambiguous and vague if one sifts through the paperwork that there is no guidance given to extended-hours trading thus it is unclear if the restrictions would not go into place until 9:30AM ET and/or if theyâd be valid outside of the traditional 9:30AM-4PM hours. So, just let this primer serve as a heads-up that if you were to day trade stocks ahead or down 10% or more on a day, the rules are changing and you need to be aware of whatâs happening.