In the case of any loss claimed to have been sustained from any sale or other disposition of shares of stock or securities where it appears that, within a period beginning 30 days before the date of such sale or disposition and ending 30 days after such date, the taxpayer has acquired (by purchase or by an exchange on which the entire amount of gain or loss was recognized by law), or has entered into a contract or option so to acquire, substantially identical stock or securities, then no deduction shall be allowed under section 165
虽然法律文字上说： within a period beginning 30 days before the date of such sale .... the taxpayer has acquired ... substantially identical stock or securities, then no deduction shall be allowed
https://www.law.cornell.edu/uscode/text/26/1091
(a)Disallowance of loss deduction
In the case of any loss claimed to have been sustained from any sale or other disposition of shares of stock or securities where it appears that, within a period beginning 30 days before the date of such sale or disposition and ending 30 days after such date, the taxpayer has acquired (by purchase or by an exchange on which the entire amount of gain or loss was recognized by law), or has entered into a contract or option so to acquire, substantially identical stock or securities, then no deduction shall be allowed under section 165
虽然法律文字上说： within a period beginning 30 days before the date of such sale .... the taxpayer has acquired ... substantially identical stock or securities, then no deduction shall be allowed
那么，如果我仅仅是5/1买了某股票，5/2全部卖掉，有loss。根据以上定义，由于5/2卖掉之前30天我买了这个股票，这个也是wash sale？道理说不通。
5/1 买200股，5/2 卖掉100股有loss, 这个loss就不能用来for tax deduction，但这个loss被剩下的100股carry，提高了成本。等剩下的100股卖掉以后，如果还有loss，可以for tax deduction。其实wash sale没有那么可怕，一般早晚可以用，如果有loss。
wash sale了。理论上没有什么区别，如果全部卖掉，报税时可以算多次买入，一次卖出。