Analyst Update: Agios Pharma, Chesapeake Energy, Fitbit

Analysts are weighing in on biotech Agios Pharmaceuticals Inc (NASDAQ:AGIO), oil-and-gas stock Chesapeake Energy Corporation (NYSE:CHK), and wearable tech stock Fitbit Inc (NYSE:FIT). Here's a quick roundup of today's brokerage notes on AGIO, CHK, and FIT.

• AGIO is down 15.8% to sit at $55.68, after reporting that early testing showed an unexpected side effect for its new drug, AG-519. Prior to the announcement, J.P. Morgan Securities issued an ill-timed price-target hike to $50 from $39. Before today, Agios Pharmaceuticals Inc had outperformed the greater S&P 500 Index (SPX)  by 67.9 percentage points over the last 60 sessions. In fact, AGIO just yesterday notched a year-to-date closing high, and could find a foothold atop its 160-day moving average, which was toppled in late May. However, the stock remains 55% lower year-over-year. Short interest in the stock is elevated, accounting for 19.9% of AGIO's float -- an amount that would take traders nearly two weeks of trading, at AGIO's average daily volume, to cover.

• CHK is feeling the pain, down 4.6% at $4.74, after a downgrade to "underperform" from "perform" by RBC. While the stock has more than tripled since its decade-plus low of $1.50 in early February, year-over-year Chesapeake Energy Corporation is down over 64%. Nevertheless, bullish sentiment still appears to dominate the options pits, with CHK's 10-day call/put volume ratio at the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE) and NASDAQ OMX PHLX (PHLX) of 4.31 sitting higher than any other reading within the past 12 months.

• FIT is trading at $14.50, up 2.8%, after Wedbush initiated coverage with an "outperform" rating and $18 price target -- territory not charted since its post-earnings bear gap in early May. Still, the stock is down 50% year-to-date, facing resistance at its 80-day moving average. Bullish sentiment towards the stock is strong, with FitBit Inc's 10-day ISE/CBOE/PHLX call/put volume ratio of 19.1 sitting in the 97th percentile of its annual range. And options players are getting some bang for their buck, with Fitbit's Schaeffer's Volatility Index (SVI) sitting in the bottom 2% of all other readings in the past 12 months, showing that near-term options are pricing in historically low volatility expectations.

For other stocks in analysts' crosshairs, read Analyst Upgrades: LinkedIn Corp, SolarCity Corp, and Pandora Media Inc and Analyst Downgrades: QUALCOMM, Inc., Restoration Hardware Holdings Inc, and Insmed Incorporated.