Biotechnology sector exchange traded funds are caught in one of their worst sell-offs, breaking below their long-term trendlines and hovering in bear market territory, as investors dump growth stocks.

The largest biotechnology-related ETF, the iShares Nasdaq Biotechnology ETF (NasdaqGM: IBB), is now trading 3.3% below its 200-day exponential moving average after plummeting 20.7% since its late February high – any decline of at least 20% since its recent high is considered bear market conditions. [Biotech Bumble: ETFs Fall to 2014 Lows]

IBB dipped below its 200-day moving average on Monday for the first time since August 2011, reports Steven Russolillo for the Wall Street Journal. [Investors Say Bye-Bye to Biotech ETFs]

The 200-day average is a key technical level used by technical analysts to gauge the market’s long-term trends. When a security dips below the trendline, observers expect further weakeness ahead.

“This is a classic case of oversold conditions, staying oversold,” Jonathan Krinsky, chief market technician at MKM Partners, said in the article. “At this point we need to see an extreme flush down to look for a tradeable low in biotech.”

Other broad biotech ETFs are also moving below their 200-day trends. The First Trust NYSE Arca Biotechnology Index Fund (NYSEArca: FBT) is 0.01% below its 200-day EMA, the SPDR S&P Biotech ETF (NYSEArca: XBI) is 10.2% below its 200-day EMA and the Market Vectors Biotech ETF (NYSEArca: BBH) is 4.3% below its 200-day EMA.