Analyst Upgrades: Symantec Corporation, Mallinckrodt PLC, and Transocean LTD

Analysts are weighing in on software stock Symantec Corporation (NASDAQ:SYMC), biotech Mallinckrodt PLC (NYSE:MNK), and oil-and-gas stock Transocean LTD (NYSE:RIG). Here's a quick roundup of today's bullish brokerage notes on SYMC, MNK, and RIG.

• SYMC is up 0.9% at $20.31, even after Google's "Project Zero" said the company's antivirus software is majorly flawed, and pointed out a "wormable vulnerability with potentially devastating consequences." SYMC shares are enjoying a boost after an upgrade to "hold" from "sell" at Evercore, following the company's Blue Coat purchase. SYMC is on a hot streak, up 18.9% in the past month, and, even prior to today, outperforming the greater S&P 500 Index (SPX) by more than 22 percentage points over the previous 40 sessions. Option buyers have been betting on a pullback, however, with Symantec Corporation's 10-day put/call volume ratio at the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE) and NASDAQ OMX PHLX (PHLX) sitting at 2.58, in the 86th percentile of its annual range.

• MNK is up 4.7% at $58.87, after BMO initiated coverage on the stock with a rating of "outperform" and a price target of $84 -- territory not explored since September. The stock could use a boost, with Mallinckrodt PLC down almost 50% year-over-year, exacerbated by a scathing analysis by Citron Research's Andrew Left. Short interest remains elevated, up 22.9% over the last two reporting periods, and now accounts for 14.2% of the stock's float -- an amount that would take 6.8 days of trading, at MNK's average daily volume, to cover. Option buyers are more bearish than usual, with MNK's 50-day ISE/CBOE/PHLX put/call volume ratio of 1.86 sitting higher than 98% of all other readings from the past 12 months.

• RIG ​is up 4% at $11.49, following an upgrade to "hold" from "sell" by Evercore, which also raised RIG's price target to $12. Further, the brokerage firm said its conviction in the current opportunity in oilfield services has only intensified amid the post-"Brexit" fallout. RIG is attempting to break north of its 200-day moving average, and even prior to today, had outperformed the SPX by over 28 percentage points over the last 60 sessions. Option bulls have been hot on the stock, with Transocean LTD's 10-day ISE/CBOE/PHLX call/put volume ratio of 1.78 sitting higher than 85% of all other readings from the past year.