From the beginning of 2013 until the most recent closing high, IBB has run up 100% and has been an important factor in the $COMPQ and $NDX rallies. Weakness in this sector is certain to impact $COMPQ and $NDX by, at minimum, stalling the rallies in these two indexes or perhaps pressuring these two indexes lower.
IBB has become extended above it's near term MA's and as you can see on the chart, when it pulls back, it likes to visit the area around the 50MA. Because the .764 Fib retrace is also right where the 50MA is, then this seems like a logical target area. A failure to hold at the 50MA would probably mean a test of the last swing low at 233. However, in the last year, IBB hasn't revisited a swing low so, unless something has changed, it isn't likely to revisit or take out the most recent swing low
There were all kinds of warnings on the chart before the most recent drop, the most important, IMHO, being the negative divergence.
For all I know, IBB may reverse on Monday but if it doesn't then watch for the to drop to 50 as that is where it has turned recently. If the doesn't stop there, then watch for a drop to 30 as an oversold signal. At the same time, watch the for a drop below -100 and then a reversal and rise back above -100 as that is generally a good signal that the decline is either over or soon will be.
The point of this exercise is that the $SOX index, with several shared components in the $COMPQ & $NDX, has been flat for the last 7 sessions, and now you have IBB exhibiting weakness. The $COMPQ & $NDX under performed the other major indexes this past week and they have been the drivers behind this rally since day one but they're not going to be able to maintain these important leadership roles if sub-sectors begin to flounder.
Added Sunday, 03/02/2014: I just read that 7 of the top 10 stocks in the Russel 2000, $RUT/IWM are biotech stocks.