<prompt> Human: I was holding shares of a pharmaceutical company for a few months now at a loss... Had planned on writing off the loss on my taxes for 2017. Well I found out today shares were up 400 Should I sell tomorrow? If so, what do I do with the money, reinvest it or ?... Kind of new to this. I had about 7500 in this company as speculation and its now worth a bit over 42,000 from my cost basis per share.  <response>: Should I sell tomorrow?The answer to this sort of question is pretty much always: would you buy it today? If youd buy it today, then you hold. If youd not buy it today, you sell. Whether its up or down is irrelevant in that decision.Long-termshort-term holdings and loss deductions and stuff complicate that decision a little, but rarely and only a little. 