Day Traders
Does the SE taxes applies to Day Traders Transaction
Does the SE taxes applies to Day Traders Transaction
Nope, see below.
"...Gains and losses from selling securities from being a trader are not subject to self-employment tax. "
Remember if they didn't properly make the 475f mark to market election, it is all Sched D and Sched A, wash sale rules, interest deduction limits and cap loss limits apply.