Zillow Group Inc (NASDAQ:Z) is sharply higher this afternoon, amid unconfirmed rumors the real estate company may be a buyout target. Among the potential suitors are Google Inc (NASDAQ:GOOGL), and possibly even Facebook Inc (NASDAQ:FB) -- following glowing comments from Z CEO Spencer Rascoff. This is likely welcome news for recent call buyers -- of which there have been many.

Specifically, during the last two weeks at the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX), Z has racked up a call/put volume ratio of 2.36. Not only does this reading indicate more than two calls have been bought to open for every put, it also ranks higher than nine-tenths of comparable metrics from the past year.

Not everyone is so convinced about Z's prospects. For one, over 36% of the stock's float is sold short -- representing more than 12 sessions' worth of trading activity, at typical volumes. In fact, it's possible some of today's call buyers -- especially those initiating positions at out-of-the-money strikes -- may be short sellers attempting to hedge their bets. For another, 80% of covering analysts consider the shares worthy of a tepid "hold" rating.

From a technical perspective, this skepticism seems justifiable. Despite Zillow Group Inc's (NASDAQ:Z) 4.1% rally this afternoon to trade at $90.52, the shares have plunged 45% since hitting an all-time high of $164.90 last July. What's more, today's gains are being contained by Z's descending 32-day moving average.

It's been a rocky year for Twitter Inc (NYSE:TWTR). Things started well enough for the shares, as they were up more than 44% as of April 27. Things turned south, however, when the company's first-quarter earnings leaked early, and since the stock's subsequent 25.7% bear gap on April 28, TWTR has been trending lower -- and touched an annual low of $33.51 earlier this week. 

Today, however, the shares are up 4.2% at $36.11, amid lingering M&A rumors and after the company said it's testing Curator, a new platform that will make it easier for publishers to track users' tweets about their content, while also allowing users to make purchases using interactive features.  What's more, the stock is attempting to claw its way into the black year-to-date.

Judging by today's price action, traders are applauding the e-commerce feature, the first major change since Dick Costolo stepped down as the company's CEO. Option traders, too, seem bullish, as more than 200,000 calls have crossed today, compared to just 68,000 expected. And, even with June options expiration on the horizon, some speculators are apparently opening new bullish bets.

The most active is the weekly 6/26 36-strike call, which it appears traders are purchasing to open, expecting TWTR to extend its gains above $36 before the contracts expire at the close next Friday. 

Now is an opportune time to grab some TWTR options, too, judging by its Schaeffer's Volatility Index (SVI) of 34%, which ranks in the 11th percentile of its annual range. In other words, the stock's short-term options are attractively priced right now, from a volatility standpoint. Plus, TWTR's Schaeffer Volatility Scorecard (SVS) of 96 indicates the stock has tended to make outsized moves, compared to what the options market has priced in during the past year. 

Today's focus on calls isn't a new phenomenon, though, as Twitter Inc's (NYSE:TWTR) short-term option traders were more call-skewed than usual coming into today, according to its Schaeffer's put/call open interest ratio (SOIR). This reading of 0.58 is lower than four-fifths of all others taken in the past year. 

U.S. markets are poised to end the week on a high note, despite ongoing uncertainty over Greece's economic fate. In company news, today's stocks to watch include Chef Boyardee maker ConAgra Foods Inc (NYSE:CAG), biopharmaceutical firm Gilead Sciences, Inc. (NASDAQ:GILD), and chocolate champion Hershey Co (NYSE:HSY). 

• Jana Partners has taken a 7.2% stake in CAG, calling the stock "undervalued." The activist hedge fund also intends on nominating three people to ConAgra Foods Inc's board of directors to address the company's "persistent underperformance." The shares, however, certainly haven't underperformed -- rallying more than 33% year-over-year to settle yesterday at $39.12, after hitting a record high of $39.37. On the news, CAG is set to open at another all-time peak, up 4.8% in electronic trading. This could pave the way for a round of positive analyst notes, as 75% of brokerage firms consider the stock a "hold" or worse, and its consensus 12-month price target of $36 is below current levels. This morning, in fact, Bernstein upped its price target on CAG to $44 from $37.


• GILD's patent application for hepatitis C drug Sovaldi has reportedly been rejected by China. Meanwhile, the drugmaker's stock has soared nearly 29% in 2015 to rest at $121.21, benefiting in recent weeks from its supportive 10-day moving average, and just yesterday notching a new record high of $121.78. This technical tenacity hasn't prevented traders from buying to open puts over calls at a faster-than-usual clip. During the last 10 days at the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX), Gilead Sciences, Inc. has amassed a put/call volume ratio of 0.74 -- higher than 93% of comparable readings from the past 12 months.


• It's been a bad year for HSY, down 11.2% at $92.26. Things are about to get worse this morning, as the shares are pointed 2.4% lower ahead of the bell, after the company reduced its full-year sales growth forecast and announced 300 employees will be laid off by year-end. This expected southward move will have the stock dangerously close to annual-low territory. This could be bad news for recent call buyers. During the last 50 sessions at the ISE, CBOE, and PHLX, Hershey Co has racked up a call/put volume ratio of 2.80, which sits just 4 percentage points from a 12-month peak.

On one hand, everybody and their local billionaire are taking cover for the next market crash. For today's piece of evidence, I bring you this, from Steven Sears: 

"Major investors are preparing for the stock market to collapse.

In the past 10 days, these investors have quietly amassed significant CBOE Volatility Index (ticker: VIX) call positions. The VIX, commonly referred to as the "fear gauge," spikes in times of volatility. Call options, therefore, increase in value when stock prices plummet. Think of the options as catastrophic insurance policies. These trades are captivating the options market.

With the VIX now just below 15, top positions over the past two weeks include July calls at 17, 22 and 23, and August 17 and 23 calls. In recent trading, an investor bought 100,000 calls in apparent anticipation VIX will spike above 26 before the end of July. A trade of that size is not a retail investor's move -- that's an institution or someone running a significant portfolio." 

On the other hand, thanks to yesterday's rally, we now have yet another week of churn in the S&P 500 Index (SPX). We're right where we were this time last week … and on May 26 … and on April 24 … not to mention Feb. 25. 

In that light, it makes sense that investors' most popular opinion is that they have no opinion. In fact, the number of self-identified "neutral" investors in the American Association of Individual Investors (AAII) sentiment survey just fell beneath 45% for the first time in 10 weeks. 

All of which leads to a burning question. If no one has an opinion, then who is out there buying all these CBOE Volatility Index (VIX) futures and VIX calls?

The answer is likely that we're considering two separate questions. Opinions are interesting, but at the end of the day, maybe they don't mean that much. The VIX Frenzy, however, shows how many are voting with their actual money. And they're "betting" that actual money on a market dip and a volatility rip. 

Now, it's important to note that in the larger scheme of things, the volatility market is very small. You can buy a lot of VIX calls for a relatively low amount of money. Tracking those bets does give us insight into the marketplace, and it's an apples-to-apples comparison in that we see what they're doing in VIX now vs. other points in time. But at the end of the day, it's not a gigantic dollar commitment. 

So where does that leave us? We can't fully trust sentiment numbers, because those don't necessarily reflect actual behavior, but we also can't fully trust numbers like this VIX data because they're just not large enough.

I guess we have to use some intuition. I'm with those that say the rally remains hated and distrusted, and expectations for future volatility outstrip any and every measure of actual volatility. I'm not real sure we keep rallying in spite of all that. I mean, we stop around here every time. But I do believe that in a day or three when we inevitably start obsessing over the next Greece news or potential Fed hike, it puts a natural floor in until we see bullishness tick up.

Disclaimer: Mr. Warner's opinions expressed above do not necessarily represent the views of Schaeffer's Investment Research.

Analysts are weighing in on software solution specialist Red Hat Inc (NYSE:RHT), biotechnology firm Momenta Pharmaceuticals, Inc. (NASDAQ:MNTA), and alternative energy issue First Solar, Inc. (NASDAQ:FSLR). Here's a quick roundup of today's bullish brokerage notes on RHT, MNTA, and FSLR.

• RHT last night reported first-quarter earnings that beat analysts' estimates, and Wall Street responded in kind. Specifically, the stock received no fewer than eight price-target hikes, including one from Cantor Fitzgerald to $90 from $85. This represents expected upside of 12.5% to current trading levels. Amid this bullish backdrop, the shares are up 1.8% out of the gate at $79.98, and just tagged a fresh 15-year high of $80.46. Technically speaking, the security has now tacked on 15.6% year-to-date. Option traders, meanwhile, have been bracing for a pullback by buying to open puts over calls at a rapid-fire rate in recent months. In fact, Red Hat Inc's 50-day International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX) put/call volume ratio of 0.56 ranks just 2 percentage points from a 52-week peak.


• Biotechs have had a big week, and today, MNTA is in the spotlight. The stock is up 1.2% at $24.70 out of the gate, after the company's U.S. launch of its generic multiple sclerosis drug was met with upwardly revised price targets from Brean Capital (to $31) and Stifel (to $29). The equity has been on fire since hitting its year-to-date low of $10.22 in early February, more than doubling in value. Additionally, the stock tagged the $25.56 mark this morning -- its loftiest perch since July 2010. A continued rise may prompt short sellers to start throwing in the towel, which could spell additional gains for Momenta Pharmaceuticals, Inc. down the road. Nearly 17% of the security's float is sold short, representing six sessions' worth of pent-up buying demand, at average daily volumes.


• FSLR is up 1.3% in early trading, after Needham upped its price target on the shares to $73 from $69. The brokerage firm cited the successful IPO of 8Point3 Energy Partners (CAFD) -- a yieldco formed between FSLR and SunPower Corporation (NASDAQ:SPWR) -- as the catalyst, saying CAFD is "uniquely positioned as a solar-only yieldco with joint sponsorships by two of the largest solar developers in the world." Separately, CAFD priced its IPO at $21 per share this morning. On the charts, the shares of FSLR have been gaining ground since bouncing in the $49 region last week, up more than 7% to trade at $52.64. Option traders have been rolling the dice on more upside, too. At the ISE, CBOE, and PHLX, for example, First Solar, Inc.'s 10-day call/put volume ratio of 5.29 rests in the 99th annual percentile. In other words, calls have been bought to open over puts with more rapidity just 1% of the time within the past year.

Analysts are weighing in today on oil giant BP plc (ADR) (NYSE:BP), biotech stock BioMarin Pharmaceutical Inc. (NASDAQ:BMRN), and optical components specialist Finisar Corporation (NASDAQ:FNSR). Here's a quick roundup of today's bearish brokerage notes on BP, BMRN, and FNSR. 

• BP is up fractionally this morning at $41.27, following a downgrade to "sector perform" from "outperform" at RBC. After an underwhelming 2014, the stock has picked up the pace, adding over 8% year-to-date. In the meantime, call buying has hit a near-annual-high clip. That is, at the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX), BP plc's 10-day call/put volume ratio stands at 35.89, which is only 1 percentage point from an annual bullish high.


• It's been an interesting morning for BMRN, which is off 2.4% to trade at $135.27. First, Baird cut its outlook to "neutral," but raised its price target to $133 from $125. Plus, Wedbush raised its price target to $130. Obviously, both of these price targets represent a discount to current trading levels for the stock, which has easily doubled in value during the past 12 months. What's more, BMRN touched an all-time high of $140.49 just yesterday, thanks to well-received drug news and a round of upbeat analyst attention. Today's mixed analyst notes echo the withstanding sentiment. For example, 12 of 14 brokerage firms rate BioMarin Pharmaceutical Inc. a "buy" or better, while short interest rose over 16% during the two most recent reporting periods.


• FNSR has fallen 8.6% this morning to trade at $20.25, as the Street responds to the company's fiscal fourth-quarter earnings numbers. No fewer than six brokerage firms have weighed in on the stock, but most have actually raised their price targets. Not Raymond James and Jefferies, though. The former lowered FNSR to "outperform," while the latter reduced its target price to $21 from $22.  The shares have been strong since touching an annual low of $14.22 on Oct. 13, adding 42.4%. Still Finisar Corporation remains heavily shorted. The 9% of the stock's float controlled by short sellers represents over three weeks' worth of buying power, at normal daily volumes. 

Tesla Motors Inc's (NASDAQ:TSLA) popular Model S sedan is headed to toy stores around the country, thanks to a deal with Mattel, Inc. (NASDAQ:MAT). Specifically, miniature versions of the electric car will be produced by MAT brands Hot Wheels and Matchbox, as confirmed yesterday on Twitter Inc (NYSE:TWTR).

Our 1:64 Tesla Model S is joined by the real thing! #OrangeIsTheNewTrack @TeslaMotors #HotWheelsTesla pic.twitter.com/QKxlJ5AnVP

— Hot Wheels (@Hot_Wheels) June 18, 2015

The collaboration marks a milestone for TSLA, which has gone from automotive afterthought to iconic name in just a few short years. What's made the company even harder to ignore is its stock's tremendous run on the charts. Since bottoming at $181.40 in late March, the shares have surged 44% to trade at $261.18, and are approaching levels not seen since last October.

More upside could be in store, as well, given Tesla Motors Inc's (NASDAQ:TSLA) high levels of short interest. Over one-quarter of the stock's float is sold short, representing nearly eight days' worth of pent-up buying demand, at typical daily volumes. Should these bears start hitting the exits, it could supercharge TSLA's drive higher.

Shares of MAT haven't been nearly so successful. The toymaker's stock is down more than 13% year-to-date at $26.80, and it's currently struggling to muscle above its 160-day moving average.

Nevertheless, traders at the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX) have been bullish toward Mattel, Inc. (NASDAQ:MAT). The equity's 10-day call/put volume ratio of 3.27 outranks 84% of comparable readings from the past year. A capitulation among these bullish bettors could result in headwinds.

We're coming off the hottest May on record (or, second-hottest depending on the source), and all signs suggest 2015 is easily on pace to beat out 2014 for the warmest year since the data began being compiled. As societies scramble to adjust to global warming, alternative energy stocks could come into play -- especially with a number of initial public offerings on the horizon. One such stock that has the potential to run higher in the near term is Sunedison Inc (NYSE:SUNE).

Already, SUNE has been a technical standout, boasting a 61% year-to-date lead. Yesterday, in fact, the stock topped out at a six-year high of $31.80, on reports its yieldco -- Terraform Global (GLBL) -- raised its IPO to up to $800 million. (Last night, GLBL said it priced its IPO at $38 per share.) Today, the security is pulling back from this notable milestone, down 0.4% at $31.40, but considering peak call open interest in the June series is located at the 31.50 strike, the security could be contained beneath this level through tonight's close, when the front-month contracts expire.

While there is a significant amount of open interest at the June 31.50 call (25,333 contracts to be exact), option traders have shown a growing interest in long puts in recent weeks -- although some of them may be protective in nature. At the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX), for example, SUNE's 10-day put/call volume ratio has jumped to 1.10 from 0.24 over the past two weeks. What's more, the current ratio ranks in the 82nd annual percentile, meaning puts have been bought to open over calls at a faster-than-usual clip. An unwinding of these bearish bets could help SUNE resume its longer-term uptrend.

This skepticism has spilled outside of the options pits, as well. Although short interest plunged 20.7% during the most recent two-week reporting period, it still accounts for more than 29% of SUNE's available float. In fact, it would take more than six sessions to cover the remaining shorted shares, at average daily trading levels, leaving the door wide open for a short-covering rally.

Sunedison Inc (NYSE:SUNE) could also benefit from an additional round of price-target hikes. On Tuesday evening, Needham -- which weighed in on First Solar, Inc. (NASDAQ:FSLR) this morning -- upped its target price to $36 from $34, territory not charted since September 2008. For the sake of comparison, the average 12-month price target on SUNE is $34.85, a lukewarm 11% premium to current trading levels.

Cyberark Software Ltd (NASDAQ:CYBR), FireEye Inc (NASDAQ:FEYE), and Palo Alto Networks Inc (NYSE:PANW) each touched new highs today, lifted by broader market tailwinds. This isn't anything new -- cybersecurity stocks have been on fire lately. However, there are reasons to believe more upside could be in store.

• Despite CYBR's 86.4% year-to-date advance to trade at $73.89 -- and new record high of $76.35 -- 63% of covering analysts rate the stock a "hold" or worse. What's more, the equity's consensus 12-month price target of $60.80 stands at a nearly 18% discount to current levels. This could pave the way for a round of bullish analyst notes, which could boost Cyberark Software Ltd to even higher highs.


• Similarly, FEYE shot to an annual peak of $55.33 earlier, and was last seen 1% higher at $54.62 -- bringing its year-to-date lead to 73%. What's more, the shares have been riding atop support from their 10-day moving average for the past month. Nevertheless, almost half of the analysts tracking FireEye Inc rate it a "hold" or worse, and its average 12-month price target of $50.07 rests below the stock's current perch. In other words, these shares could benefit from upgrades and/or price-target hikes, as well.


• Finally, PANW is fresh off an all-time high of $183.96, up 1.2% at $182.71 -- thanks to a $20 price-target hike to $200 at RBC. In fact, the stock has more than doubled in value on a year-over-year basis. Nevertheless, traders at the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX) have bought to open puts over calls at a faster-than-usual clip recently, per the security's 50-day put/call volume ratio of 1.03 -- in the 65th annual percentile. A capitulation among skeptics could result in tailwinds for Palo Alto Networks Inc.

Analysts are weighing in on biopharmaceutical firms Radius Health Inc (NASDAQ:RDUS) and Juno Therapeutics Inc (NASDAQ:JUNO), as well as chronic pain specialist Nevro Corp (NYSE:NVRO). Here's a quick roundup of today's brokerage notes on RDUS, JUNO, and NVRO.

• RDUS, along with sector peer BMRN, is surging today in the wake of upbeat drug news -- moves CNBC's Jim Cramer says both stocks "deserve." Specifically, RDUS hit a record high of $63.52 earlier -- and was last seen up 17.2% at $60.63 -- after the company said late-stage study results of its osteoporosis drug were promising. Additionally, Cantor Fitzgerald boosted its price target on the shares to $71 from $58, saying the treatment has "meaningful" opportunity. Year-to-date, Radius Health Inc is now boasting a 56% lead, and short sellers could soon be ready to jump ship. A healthy 6% of the stock's float is sold short, which would take more than four sessions to cover, at average daily trading levels.


• Maxim Group initiated coverage on JUNO with a "buy" rating and a $78 price target -- representing expected upside of 49.3% to the stock's current perch at $52.25, and a move into uncharted territory. The brokerage firm cited its belief that "Juno is best equipped for success against solid tumors," and could see approval for its experimental cancer treatments by 2017. The security initially jumped more than 5%, but was more recently seen up 1.5% at $52.12 -- docked just beneath its year-to-date breakeven mark. Option traders, meanwhile, have shown a preference for long calls over puts in recent months. At the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX), speculators have bought to open 1.89 calls for every put over the past 50 sessions.


• NVRO has rallied 6.8% to trade at $53.66, after J.P. Morgan Securities raised its price target on the shares to $67 from $54. Not only does this new target price sit nearly 25% above current trading levels, but it also represents a move to all-time highs. Since going public in early November, the security has more than doubled in value -- and hit a record peak of $58.87 on May 11. However, sentiment is mixed. For starters, each of the analysts covering Nevro Corp maintain a "buy" or better rating. Elsewhere, short interest surged 15.7% in the last reporting period, and now accounts for 8.5% of the equity's available float.

It's been an up-and-down year for the Dow Jones Industrial Average (DJIA). As it stands now, the index is holding on to a 1.8% year-to-date lead. Below, we'll look at two of the Dow's 30 components, Walt Disney Co (NYSE:DIS) and Wal-Mart Stores, Inc. (NYSE:WMT), which have been its best- and worst-performing stocks in 2015, respectively. 

With its 1.4% gain today to trade at $113.10, DIS boasts a 20.1% year-to-date lead. This narrowly beats out UnitedHealth Group Inc. (NYSE:UNH), the second-best performing Dow component. Moreover, the shares touched an all-time high of $113.55 earlier.

Similar to fellow blue chips Goldman Sachs Group Inc (NYSE:GS) and Visa Inc (NYSE:V), put buying has picked up recently at the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX). Walt Disney Co's 10-day put/call volume ratio across these exchanges comes in at 0.81, which is higher than 83% of readings taken in the past year.

What's more, the stock remains heavily shorted, as the over 41 million DIS shares controlled by bears represent nearly nine sessions' worth of trading, at its average daily volumes. Even with its already impressive 2015 gains, DIS could go even higher, if some of the weaker bearish hands hit the exits. 

On the opposite end of the spectrum is WMT. Coming into today, the stock was off 15% in 2015, but it was last seen 0.5% higher at $73.07. The shares have been on a steady trek lower since their all-time high of $90.97 on Jan. 13, pressured by their descending 20- and 32-day moving averages.

Perhaps this is why 82% of analysts say Wal-Mart Stores, Inc. is a "hold" or worse. On the other hand, option traders have been betting on a breakout. The security's 10-day call/put volume ratio at the ISE, CBOE, and PHLX comes in at 5.73 -- higher than 93% of similar readings from the past 12 months.

These bulls may be in luck, too. WMT's 14-day Relative Strength Index (RSI) comes in at 35, closing in on oversold territory. Like Walt Disney Co (NYSE:DIS), Wal-Mart Stores, Inc. (NYSE:WMT) could be in store for short-term gains.

NVIDIA Corporation (NASDAQ:NVDA) options traders have rarely been more bearish than in recent weeks. According to data from the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX), speculators have bought to open twice as many puts as calls in the last 10 sessions. The resultant put/call volume ratio of 2.04 ranks just 3 percentage points from an annual peak.

There's plenty of skepticism elsewhere, too. Fifteen of 21 analysts tracking NVDA consider it a "hold" or worse, and the stock's consensus 12-month price target of $22.42 stands at a slim 2.2% premium to its current perch at $21.92. If that's not enough, despite short interest plummeting 35% during the latest reporting period, it still accounts for a healthy 8.6% of NVDA's float. At average daily trading volumes, it would take shorts more than one week to buy back all their shorted shares.

This is surprising, considering the security has advanced 9.3% year-to-date. What's more, NVDA recently took a bounce off its 160-day moving average, which has historically been bullish. After nine of the last 10 signals, the semiconductor stock has rallied in the ensuing 21 sessions -- averaging a gain of 5.7%. Should history repeat itself, NVIDIA Corporation (NASDAQ:NVDA) could see further upside as option bears, shorts, and skeptical analysts change their tune.