I bought 1000 shares of xop in 2015, at that time the oil price is around 50. I has been holding it ever since. now the oil price is higher than in 2015, but xop only worths 15. I lost 37000 on the 1000 shares. why is xop so bad?
Because stuff happened between the time you bought until now. Like wars, airstrikes, shale output, elections, pipelines, OPEC meetings, and, oh, demand reduction because of a virus or 3.
For OP... According to the description of the SPDR, XOP = oil exploration companies... as opposed to production/services, refining, distribution, et al, XOP will more-or-less track the price of oil, but will trade its own technical dynamics. XOP has been downtrending badly. Hopefully you mama taught you, "don't buy stocks in a down trend".