The 20 stocks listed in the table below are the S&P 500 Index (SPX) components that have attracted the highest weekly options volume during the past 10 trading days. Names highlighted are new to the list since the last time the study was run, and data is courtesy of Schaeffer's Senior Quantitative Analyst Rocky White. One name of notable interest today is Yahoo! Inc. (NASDAQ:YHOO), where weekly calls are being targeted.

As we approach midday, Yahoo! Inc. options are trading at a nearly 30% mark-up to typical intraday levels. Moreover, weekly calls are in focus, making up eight of the 10 most active strikes. The weekly 11/28 44-strike call has seen the most action so far -- largely thanks to a 10,000-contract block that was exchanged just minutes ago, and appears to be tied to stock.

Meanwhile, the next most active option is the weekly 10/31 43.50-strike put, where roughly 6,900 contracts are on the tape. The majority crossed at the bid price, implied volatility is higher, and volume outstrips open interest, collectively suggesting sell-to-open activity -- a portion of which is confirmed by data from the International Securities Exchange (ISE). In sum, these put writers expect YHOO to maintain its perch atop $43.50 through the end of this week, when the weekly contracts expire.

On the charts, Yahoo! Inc. (NASDAQ:YHOO) has added 2.5% so far to trade at $44.60, and earlier tagged a new 14-year high of $44.64. As such, delta on the put has plummeted to negative 0.23 from negative 0.49, meaning the options market is giving the put a less than 1-in-4 chance of being in the money at expiration.

Vanda Pharmaceuticals Inc. (NASDAQ:VNDA) is down 3% this morning at $10.77, after lowering its guidance -- and despite posting a narrower-than-expected third-quarter loss. In fact, the stock has been down by as much as 14.2% today -- and was placed on the short-sale restricted (SSR) list. Things were quite different last Friday, when the shares rallied 7.6%, prompting traders to flood VNDA's options pits.

Looking more closely at Friday's action, contracts crossed at triple the usual daily rate. Additionally, the equity's 30-day at-the-money implied volatility (IV) spiked 15.6% to 109.3%, signaling elevated demand for short-term strikes.

Most active by a healthy margin was VNDA's November 13 call. Two-thirds of the 1,980 contracts traded did so at the ask price, IV popped, and open interest added 1,461 contracts over the weekend. All things considered, it's safe to assume new bullish bets were initiated at the out-of-the-money strike. Alternatively, it's possible the calls were bought to serve as an upside hedge, as 43.4% of the equity's float is sold short.

In a nutshell, Friday's buyers expect Vanda Pharmaceuticals Inc. (NASDAQ:VNDA) to topple $13 by the close on Friday, Nov. 21, when front-month options expire. However, the stock hasn't explored these levels in more than a month. As such, delta on the call is just 0.24, denoting a slightly less than 1-in-4 chance the option will be in the money at expiration.

The shares of Rite Aid Corporation (NYSE:RAD) are fractionally higher at $4.80 this morning, as traders weigh reports that the company -- along with peer CVS Health Corp (NYSE:CVS) -- recently disabled Apple Inc.'s (NASDAQ:AAPL) Apple Pay system. In the options pits, speculators are scrambling to bet on RAD's short-term trajectory.

Specifically, RAD's 30-day at-the-money implied volatility (IV) has jumped 5.4% to 44.8%, underscoring the growing demand for short-term contracts. Calls have outnumbered puts by a margin of more than 2-to-1.

Digging deeper, it looks like bulls are buying to open the weekly 11/7 5-strike call, where IV rocketed 14.2 percentage points higher at the time of the biggest trade, and nearly all the contracts have crossed on the ask side. By purchasing the calls at a volume-weighted average price (VWAP) of $0.10, the speculators will reap a reward if RAD topples $5.10 (strike plus VWAP) by the close on Friday, Nov. 7, when the weekly series expires -- which also encompasses Rite Aid's monthly sales release on Thursday, Oct. 30. Risk is limited to the initial premium paid for the calls, should RAD remain south of the strike through the option's lifetime.

Bears, meanwhile, are buying to open the weekly 11/28 4.50-strike put, at a VWAP of $0.15. In order to profit on the play, the buyers need RAD to breach $4.35 -- which would mark a new annual low -- by the closing bell on Friday, Nov. 28. Again, risk is capped at the VWAP, should the equity stay north of the strike through expiration.

On the charts, Rite Aid Corporation (NYSE:RAD) has shed more than 44% since touching a decade-plus peak of $8.61 in June. Nevertheless, ISI Group this morning launched coverage with a "buy" recommendation. However, RAD is no stranger to upbeat analyst attention; half the brokerage firms following the beleaguered equity maintain "buy" or better opinions, and the consensus 12-month price target of $6.75 represents expected upside of 41% to RAD's current price. Should the security continue to struggle, a flood of downbeat analyst attention could exacerbate selling pressure on the shares.

Caterpillar Inc. (NYSE:CAT) added nearly 5% last week, thanks to a strong showing in the earnings confessional. Against this backdrop, one option speculator on Friday readjusted her long call position to gamble on additional upside for CAT in the near term.

Specifically, a sweep of 1,750 weekly 10/31 102-strike calls was bought to open in afternoon trading. This lot traded simultaneously with a symmetrical block of weekly 10/24 98-strike calls, which were set to expire at last Friday's close. In other words, it appears this trader may have rolled her bullish bet up and out one week, expecting the stock to rally past $102 by this Friday's close, when the weekly 10/31 series expires.

From a wider sentiment perspective, option traders have taken the bearish route toward an equity that's tacked on 7.7% in 2014 to trade at $97.78. At the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX), for example, the stock's 50-day put/call volume ratio of 2.08 ranks in the 97th annual percentile. Echoing this skepticism outside of the options pits is Raymond James, which cut its price target for Caterpillar Inc. (NYSE:CAT) to $105 from $110 this morning, while underscoring its "market perform" rating.

The 20 stocks listed in the table below have attracted the highest total options volume during the past 10 trading days. Names highlighted are new to the list since the last time the study was run, and data is courtesy of Schaeffer's Senior Quantitative Analyst Rocky White. One name of notable interest today is streaming video giant Petroleo Brasileiro Petrobras SA (ADR) (NYSE:PBR), which is being targeted by short-term options bears ahead of Brazil's weekend elections.

It's been a wild month for Petroleo Brasileiro Petrobras SA (ADR), with the stock moving in concert with the speculation surrounding this Brazil's presidential election. On the last trading day before voters head to the polls on Sunday, optimism abounds -- and PBR's 7.5% pop today is proof.

It's quite a different story in the equity's options pits, though, with put volume running at two times what's typically seen at this point in the day. Meanwhile, the stock's 30-day at-the-money (ATM) implied volatility (IV) has surged 14.9% to 122.2% -- in the 95th percentile of its annual range -- signaling elevated demand for the security's short-term contracts.

Most active is PBR's November 13 put, where 12,487 contracts have changed hands. A healthy portion of these ATM strikes have gone off at the ask price, and IV is up 10.3 percentage points, suggesting new positions are being purchased. Delta on the put is docked at negative 0.43, indicating a 43% chance the option will be in the money at the close on Friday, Nov. 21 -- when the front-month contracts expire.

From a wider sentiment perspective, today's accelerated put activity is just more of the same for a stock that's shed about 38% since hitting an annual high of $20.94 on Sept. 3, with the shares last seen near $13.05. In fact, at the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX), PBR's 50-day put/call volume ratio of 0.41 ranks in the 94th annual percentile. Simply stated, puts have been bought to open over calls on Petroleo Brasileiro Petrobras SA (ADR) (NYSE:PBR) with more rapidity just 6% of the time within the past year.

GameStop Corp. (NYSE:GME) has added 1.6% this afternoon to trade at $41.92. In fact, the shares have rallied sharply since hitting a month-to-date low of $35.82 on Oct. 15, tacking on 17%. Option traders are responding to this technical strength by rolling the dice on additional upside in the stock.

Taking a quick step back, GME calls are crossing at six times the level typically seen at this point in the day. Also, the equity's 30-day at-the-money implied volatility has popped 6.5% to 46.4%, suggesting short-term strikes are being targeted. Along those lines, the security's most active option is the front-month November 43.50 call, where nearly 5,500 contracts are on the tape.

Approximately 70% of these calls have traded at the ask price, and volume outstrips open interest, making it safe to assume bullish bets are being bought to open. This theory is also underscored by Trade-Alert and data from the International Securities Exchange (ISE). In short, these option bulls anticipate GME will topple $43.50 by the close on Friday, Nov. 21, when the options expire.

It's worth noting that 31% of GameStop Corp.'s (NYSE:GME) float is sold short. At the stock's typical daily trading volume, these bearish bets would take more than three weeks to cover. In other words, if GME can sustain its upward momentum, there's plenty of sideline cash available to boost the shares even higher. A potential catalyst could be the company's upcoming turn in the earnings confessional, scheduled between Wednesday, Nov. 19, and Monday, Nov. 24.

Three stocks seeing notable options activity today are at-home beverage maker SodaStream International Ltd (NASDAQ:SODA), shipping issue DryShips Inc. (NASDAQ:DRYS), and cloud concern NetSuite Inc (NYSE:N). Here's a look at how speculators are placing their bets on SODA, DRYS, and N.

• After spending most of the morning churning around breakeven, SodaStream International Ltd (NASDAQ:SODA) took off shortly before lunchtime, and was last seen 15.9% higher at $24.55, following reports of a partnership with PepsiCo, Inc. (NYSE:PEP). Against this backdrop, call players are once again flooding SODA's options pits, with volume running at 10 times the average intraday pace, and based on the equity's 30-day at-the-money (ATM) implied volatility (IV) -- which is up 18% to 74.5% -- short-term contracts are in high demand. Drilling down, buy-to-open activity has been detected at SODA's November 25 call, as traders gamble on an extended rise over the next four weeks -- a time frame that encompasses the company's third-quarter earnings report, slated for release ahead of next Wednesday's open.


• Having a decidedly different day is DryShips Inc. (NASDAQ:DRYS), which has plunged 22% to churn near $1.57 -- music to the ears of option bears -- after the company priced its new share offering at a 30% discount to last night's closing price of $2.00. Today's bearish gap -- which landed the stock on the short-sale restricted (SSR) list -- only highlights DRYS' longer-term technical troubles, with the shares down 45% year-over-year. However, during that time, the stock has never traded below the $1 mark, which may be why one speculator today bet big on this level to hold as a floor over the next 15 months. Specifically, a massive block of 19,360 January 2016 1-strike puts was sold to open earlier for $0.20 apiece, resulting in an initial credit of $387,200 (number of contracts * premium collected * 100 shares per contract). This also represents the maximum reward on the play, should DRYS maintain its foothold atop the dollar mark through January 2016 options expiration.


• NetSuite Inc (NYSE:N), meanwhile, has rallied 12.4% to $104.45 -- and moved back into the black on a year-to-date basis -- after offering up a better-than-expected quarterly earnings report and an upbeat outlook for the current quarter. What's more, the stock received no fewer than nine price-target hikes in the wake of its results, including one from Credit Suisse to $125 from $115, with the brokerage firm underscoring its "outperform" rating. On the options front, overall volume has soared to seven times what's typically seen at this point in the day, and following last night's scheduled event, the equity's 30-day ATM IV has plunged 23.8% to 33.4%. New positions are being initiated at the stock's November 115 call and November 90 put, but it appears both may be seeing sell-to-open activity.

The 20 stocks listed in the table below are the S&P 500 Index (SPX) components that have attracted the highest weekly options volume during the past 10 trading days. Names highlighted are new to the list since the last time the study was run, and data is courtesy of Schaeffer's Senior Quantitative Analyst Rocky White. One name of notable interest today is Ford Motor Company (NYSE:F), where options traders are eyeing the $14 level.

Ford Motor Company is off 3% this morning at $13.97, following its third-quarter earnings report. While the company posted an earnings beat, poor results in Europe and Russia -- as well as costs associated with transitioning its F-150 pickup to aluminum from steel -- are weighing on the shares.

Nevertheless, options traders are taking an upbeat approach to F, with calls crossing at a 46% mark-up to the average intraday rate, and outnumbering puts by a nearly 4-to-1 margin. What's more, the stock's 30-day at-the-money implied volatility has edged 1.3% higher to 27.9%, signaling elevated demand for short-term strikes.

Looking more closely, F's two most action options are the weekly 10/31 and 11/14 14-strike calls, where more than 7,000 total contracts have been exchanged. The majority have traded at the ask price, and volume outstrips open interest, pointing to buy-to-open activity. In other words, these speculators anticipate Ford Motor Company (NYSE:F) will muscle back atop $14 by the respective expiration dates.

Biopharmaceutical firm Arrowhead Research Corp (NASDAQ:ARWR) has struggled on the charts lately, exacerbated by a roughly 44% plunge on Oct. 8, due to poorly received mid-stage trial results of the company's hepatitis B treatment. Since then, the shares have largely churned around $7, closing last night at $6.92. However, one group of traders yesterday wagered on short-term upside for the stock.

Diving right in, calls were exchanged at a 26% mark-up to typical daily levels on Thursday. Also, ARWR's 30-day at-the-money implied volatility rose 8.6% to 132.7%, hinting at elevated demand for short-term strikes. In fact, eight of the security's 10 most active options belong to the front-month November series.

Leading the way was ARWR's November 9 call, where 2,227 contracts changed hands. Almost all traded at the ask price, and open interest jumped overnight, suggesting bullish bets were freshly initiated. In other words, these option players believe ARWR will topple $9 by the close on Friday, Nov. 21, when front-month options expire. Of course, it's possible some of these buyers are short sellers attempting to hedge, considering 27.4% of the stock's float is sold short.

On the fundamental front, the call's lifetime encompasses Arrowhead Research Corp's (NASDAQ:ARWR) fiscal fourth-quarter earnings report, due out between Tuesday, Nov. 10, and Friday, Nov. 14. The Street is expecting a per-share loss of 24 cents from the biopharmaceutical company.

King Digital Entertainment PLC (NYSE:KING) is up 2% this afternoon at $11.50, but remains a long way from its March IPO price of $20.50. Nevertheless, the positive price action is luring options traders to the table -- especially on the call side, where volume is running at nearly quadruple the expected intraday rate.

Digging deeper, the two most active strikes are the November 12.54 and 11.54 calls, where 1,911 and 629 contracts have traded, respectively -- mostly at the ask price, suggesting buyer-driven volume. Opening activity is a possibility at the higher-strike call, according to Trade-Alert -- which speculates short sellers may be initiating the positions to act as hedges, ahead of KING's upcoming earnings report, the night of Thursday, Nov. 6. Meanwhile, buy-to-open action is more clear-cut at the lower-strike call, as volume outstrips open interest.

As alluded to, King Digital Entertainment PLC (NYSE:KING) -- maker of "Candy Crush Saga," and as of yesterday on Facebook Inc (NASDAQ:FB), "Candy Crush Soda Saga" -- has been a technical disaster since publicly debuting. In fact, the shares have underperformed the broader S&P 500 Index (SPX) by 40 percentage points during the past three months. It's no wonder, therefore, that one-quarter of KING's total float is sold short.

The 20 stocks listed in the table below are the S&P 500 Index (SPX) components that have attracted the highest weekly options volume during the past 10 trading days. Names highlighted are new to the list since the last time the study was run, and data is courtesy of Schaeffer's Senior Quantitative Analyst Rocky White. One name of notable interest today is Microsoft Corporation (NASDAQ:MSFT), as traders up the bearish ante ahead of the company's after-the-close quarterly earnings report.

As noted, Microsoft Corporation will follow in the footsteps of a number of its fellow Dow components when it steps into the earnings confessional after tonight's close. Traders are flooding the stock's options pits ahead of the results, but -- despite MSFT averaging a single-session post-earnings gain of 2.1% over the past four quarters -- many are betting on some earnings-induced turbulence through week's end.

Taking a quick step back, overall volume is running at two times the average intraday pace, with puts having a roughly 8,000-contract lead over calls. Two of MSFT's five most active options expire at Friday's close, with the equity's 10/24 46.50-strike call seeing the most action out of this duo. However, the majority of these calls went off at the bid price, implied volatility (IV) has soared 22.1 percentage points, and volume outstrips open interest, pointing to sell-to-open activity. By writing the calls, traders expect MSFT to stay south of the $46.50 through tomorrow's close, when the series expires.

Elsewhere, MSFT'S weekly 10/24 44.50-strike put has received notable attention, with 6,289 contracts on the tape at last check. A large portion of these puts traded at the ask price, IV is up 22.4 percentage points, and volume exceeds current levels of open interest. Summing it all up, it seems new positions are being purchased. Delta on the put is docked at negative 0.41, suggesting a roughly 2-in-5 chance the option will be in the money at expiration.

Today's skeptical stance among option traders is just more of the same for a stock that's up roughly 20% year-to-date to trade at $44.88. In fact, at the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX), the security's 50-day put/call volume ratio of 0.90 ranks in the highest percentile of its annual range. Should Microsoft Corporation (NASDAQ:MSFT) turn in another well-received earnings report, an unwinding of these bearish bets could create a tailwind for the shares.

Three stocks seeing notable options activity today are optical networking equipment provider Infinera Corp. (NASDAQ:INFN), athletic apparel maker Under Armour Inc (NYSE:UA), and industrial metal concern AK Steel Holding Corporation (NYSE:AKS). Here's a look at how speculators have been placing their bets on INFN, UA, and AKS.

• A strong quarterly showing from Infinera Corp. (NASDAQ:INFN) helped send shares to a fresh six-year peak of $13.41 earlier, with INFN last seen 26.3% higher at $13.39. Adding to the bullish buzz is a round of brokerage notes, including a price-target hike to $14 from $13 at Goldman Sachs, and a spot on the brokerage firm's coveted "Conviction Buy" list. In the options pits, calls are trading at 24 times the average intraday rate, and are outpacing puts by a nearly 12-to-1 margin. A number of speculators are betting on more upside for INFN over the next several months, by buying to open the equity's December 12 call and January 2015 13-strike call.


• Also trading higher in the wake of its quarterly results is Under Armour Inc (NYSE:UA), which is up 0.2% at $66.18. Today's positive price action is just more of the same for UA, which has rallied nearly 52% in 2014, and tagged a record peak of $73.42 as recently as Sept. 8. Following this morning's scheduled event, the stock's 30-day at-the-money implied volatility has plunged 32.1% to 32.2%. This sharp drop in volatility may be what is prompting speculators to close out their short November 66 puts at a profit. In fact, a number of these positions were sold to open yesterday for a volume-weighted price (VWAP) of $3.04, and today are being bought to close at a VWAP of $2.26.


• AK Steel Holding Corporation (NYSE:AKS) is following in the bullish footsteps of the broader equities market today, and was 5.5% higher at last check to linger near $7.13. The equity has put in a solid showing in recent sessions -- thanks to an upbeat outlook from Nomura last Friday -- and is on pace to notch a nearly 13.8% week-to-date gain. Options traders think this momentum will continue over the next four weeks -- a time frame which includes the company's early morning earnings report on Tuesday, Nov. 4. Specifically, 56% of AKS' call volume this morning has centered at the November 7 strike, where it appears the majority of the positions are being bought to open for a VWAP of $0.55.