LONDON — European stocks opened the week's final trading session in negative territory, as investors continued to weigh the ongoing conflict in the Middle East and its lasting impact on growth. The pan-European Stoxx 600 was almost 0.9% lower at 8:10 a.m. in London (4:10 ET), with all major regional bourses and most sectors — oil and gas excepted — trading in negative territory during early dealmaking on Friday. European equities ended the previous session in negative territory, with the pan-