MNST – Job search and recruitment website Monster.com, long a squeaky cog on the buyout rumor wheel, appears to have jump-started the rumor circle again following news of an alliance with iHispano, a website for Hispanic and bilingual professionals. As shares in Monster.com staged an impressive 5% advance in afternoon trading to $27.11, its implied volatility surged 20% to 70%, making it one of the day’s top implied volatility gainers. Option activity gathered pace to more than 8 times the normal level, with heavy buying in March and April calls at the out-of-the-money 30 and 35 strikes. Volume in the April calls was more than double the open interest, as traders gleefully paid 200% higher premiums to lock in share price upside in Monster.com – a share that has traded as high as $50.28 over the past 52 weeks.

NTAP – Options in Network Appliance, the maker of network data storage and information management systems, have been all over the map in recent weeks – witness the events of last Monday, when vague analyst chatter sent overall option volume to 4 times the normal level as traders piled into April 22.50 calls. In the ensuing week, its implied volatility has lurched higher by one-third, and now reads 54%. Today, with shares posting a modest 2% gain to $22.99, traders once again bought heavily into April 22.50 calls at $1.85, combining them with the sale of calls one strike higher at the 25 mark for $0.85. It also appears that volatility plays are in favor in the June contract between strikes 20 and 22.50 – a buyer of this position pays a $4.15 premium (18% of the current share price) in the expectation of a move to the upside past $26.65 or to the downside below $15.85. A seller of this position would take in the premium in anticipation of very rangebound activity between those strike prices, essentially calling the market’s bluff given the very amorphousness of the recent share price appreciation.

HLS – Options in HealthSouth Corp posted 9 times the normal level of volume today on back of a 1% decline in its share price to $15.91. Shares in HealthSouth, which provides inpatient and outpatient rehabilitation services and long-term acute care nationwide, have given up 25% of their value for the year to date, and it looks like option traders aren’t looking for any rehabilitation in its share price for the second half of the year. As much as clear from the buying interest we observed in July 15 puts, which were bought on the offer for $1.55 today, implying a 9% drop below the 52-week low just to break even.

DVA – While shares in another health-care ticker, DaVita, the operator of kidney dialysis centers, mimicked the decline in HealthSouth with a 2.6% slide to $47.55, the 12-fold increase in option volume we’re seeing today may be due to a different protective strategy.