Biotech ETF $IBB has recently broken below a rising channel, and is now threatening a critical support, a break of which can send price lower towards the 2016 lows.IBB Weekly Chart(click to enlarge)Topping:- Looking at the weekly chart, we can see that price has flattened, and broke below a rising trendline.- BUT, it is now at another key support around $100-$101. - Note that the RSI is still holding above 40 and price is still holding above the 200-day simple moving averages. - These are signs that the bullish mode could still be valid.- A break below $100, with the RSI below 40 on the other hand could reflect bulls losing control of this market.- Let's see what happens here as IBB trades at the crossroad between strong support and possible topping action.