The Best (And Worst) ETFs Of Last Week Amid Social Media's Collapse

The rug was unceremoniously pulled out from under the bulls this week as several key earnings misses and economic data surprises led to a muted decline in stocks.  The SPDR S&P 500 ETF (SPY) jostled lower for much of the week and continues to underscore the difficulty in forecasting price trends this year.  

Social media stocks Twitter Inc TWTR, LinkedIn Corp LNKD and Yelp Inc YELP were all deeply discounted after releasing fourth quarter earnings results. Investors were disappointed with recent progress and forward guidance estimates, which prompted heavy selling across the board in this sector.  

The following ETFs represent a sample of the best- and worst-performing funds over the last five trading sessions.

BEST: Greek Stocks

After months of selling, the Greek stock market rebounded this week as speculation over financial negotiations for this indebted nation took a positive turn.

Related Link: Barron's Recap: The World's Hottest Market

The Global X Funds GREK gained more than 14 percent since last Friday’s close and touched its highest levels in nearly two months.

GREK tracks the 20 largest and most liquid stocks on the Athens stock exchange.  This country-specific ETF has attracted nearly $200 million in new assets this year as deep value-seeking investors bet on a turn around.  

Despite the progress this week, GREK still has quite a ways to go in order to foster confidence in a sustainable recovery.  

WORST: Biotechnology Stocks

The biotechnology sector came under fire this week as a result of earnings reports and sentiment shifts.  Many ETFs in this sector saw some of their highest volume trading in several years as worries over big money exiting these stocks led to heighten volatility.  

The BioShares Biotechnology Clinical Trials Fund BBC experienced a drop of over 11 percent over the last five trading sessions as the smaller companies in this fund fell precipitously.  BBC contains 68 stocks engaged in early stage trials of new drugs and medical sciences.  

Other ETFs in this sector that were adversely affected include the SPDR S&P Biotech (ETF) XBI and ALPS Medical Breakthroughs ETF SBIO.