system
A chat on subreddit /r/wallstreetbets
human
In a given tax year a person's short term capital gains and short term capital losses are added together. If you make 3k on one trade then lose 3k on another your tax liability will be 0. If you make 4k on a trade and lose 2k on another your tax liability is 2k.  
  
 Now, let's say this guy stops now with his 62k gain and doesn't trade again until January 2019 where he blows it all. His tax liability for for 2018 is going to be 62k

gpt
Ah thanks the clarification. Across year is when you gotta be careful