Monday is different because the weekend is different, it probably is worth a buy because there can be some negative pricing initially which develops and on average that could result in a gain on average due to a lowered price when buying on average.      Its tempting to say Friday is a buy because quite often I think some selling ceases until the Monday again, I'm not sure if that idea will show on your chart and I would want to sell into the rise that occurs after before the possible sell orders that can occur on Monday as market open which have been closed.    I think that point of some exchanges closing and others not is like two tides meeting, theres some mix or adjustment between them.