I am not sure what to do here? closed out my positions and ended up with a short term gain of 287K how do I deal with taxes? Am I supposed to pay something upfront or get hit with a penalty? How do I figure out how much to set aside for taxes?
Depends on whether you have trader status. Cover yourself by making an estimated payment to IRS of 1/4 your gain * capital gains rate. 1040ES attached.