By Pete Najarian, co-founder of OptionMonster

King Pharmaceuticals ( KG) shares rose in after-hours trading following heavy options activity.

The options action began Wednesday morning at the $10 strikes in May, July, and October, in which calls were jumping on OptionMonster's proprietary tracking systems. The May 10 calls were particularly notable, ending the day with 11,800 contracts trading against open interest of 1,507.

King ended the regular session up 3.45% and popped another 4.82% after the close to $8.48. The stock began to rise a week ago after Goldman Sachs placed King on the firm's vaunted "Conviction Buy" list, sending the shares over their 50-day moving average and sustaining higher levels since then.

But now what? King acquired pain treatment drug Embeda when it bought rival Alpharma last December, and could be a catalyst for the stock depending on the timetable for the Food and Drug Administration, which reportedly has been reluctant to approve certain painkillers out of concern over abuse.

At the time of publication, Najarian had no positions in any stocks mentioned.

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