how do I report dependent income/loss

Filing has MFJ with son as dependent. In 2020, son had stock investments losses of -$17000. How do I report it on my return? or does son needs to file on his own. He is 26 years old, lives with me and goes to college.

 

On Sch D, there is an option, if income is for Taxpayer 1 or Taxpayer 2 (spouse)  or joint. It doesn't have my son's name listed. So does this mean, I report it has Jointly? (assuming I can claim him on my return)