some believe uptrend lines like this are weak reistance but since 2009 bottom seems like there is some validity to them. shows us what you are seeing to come to your conclusion.
I see the same as you except numerous tests suggest the validity of it holding like before is lowered. Definitely an overbought market but the bear play continues to remain crowded, Your line is found in large timeframes suggestiing even a minor breach could signify a tremendous stop run. I see it as an area to take profits but not necessarily one to short, some will disagree with this reasoning but that is what constitutes a market. As of now daily remains very healthy.
in theory the same rotation works on a multi day chart, we went up and made new highs and created a nip in the process, once the nip support has been broken, it opens the gate for the lower cleave on that bell curve....choice of longer/shorter timeframes is undefined, determined by weight of news, size of players, cooperation of corresponding indexes,or lack of,size of moves, larger one moves timeframes out