The iShares Nasdaq Biotechnology ETF (NasdaqGS: IBB), the largest biotech exchange traded fund by assets, is trading modestly lower today, but if IBB is not able to close to the upside, today will be the fourth consecutive day the fund has closed in the red.

Over the past four trading days, IBB has lost nearly 6.5%, hardly cause for alarm when it comes to an ETF with a three-year standard deviation of 18%. That is nearly double the comparable standard deviation on the S&P 500.

Although IBB’s recent skid does not even meet the standard definition of a correction, which is a 10% decline, the ETF’s late April woes do have it flirting with some critical technical support.

“IBB hit resistance line (1) on 3/20 and created a “reversal pattern at (2). Since then IBB has traded sideways and may have created a “Double Top” at the (2) reversal level. Now IBB is testing Fibonacci 423% extension level as support this morning at (3),” according to Chris Kimble of Kimble Charting Solutions.