After an ending diagonal that behaved like expected (sharp reversal after it), Ibov should find support at 55816. The main reason for this claim is that this support area is historically important. RSI should reach the uptrend support, and bounce up (any break of this level (33%) on daily RSI (14,close) should be interpreted as a first sign that the uptrend is weak). The other important point is that this support (55816) is the level of 38% of retracement for the major rally that was in place after brexit referendum.
The reason i think we should be cautious on trade this situation, is the FED possible rate hike, with next important meeting being at Sep 21. As IBov traders may know, american markets are a main driver of Ibov so i would wait to see what will happen after the meeting to take a more consistence decision. My bias, therefore, is Neutral to Long.