The following are some of the top stocks to watch for active trading today based on pre-market and after-hours volume activity. There are links through to more detailed coverage and volume analysis at VSInvestor.com:

Medarex Inc. (Nasdaq: MEDX) shares are up about 90 percent after Bristol-Myers Squibb Co. (NYSE: BMY) said it plans to buy the company for $2.4 billion, or $16 a share.

Pacific Sunwear of California Inc. (Nasdaq: PSUN) shares are getting hit on a second-quarter warning.

Orexigen Therapeutics Inc. (Nasdaq: OREX) shares are falling, and are among the most actively traded Nasdaq stocks after the company proposed a 9 million-share offering.

Celgene Corp. (Nasdaq: CELG) shares are up more than 10 percent on stronger-than-expected revenue and net procedure sales growth.

Intuitive Surgical Inc. (Nasdaq: ISRG) shares are up strongly on better-than-expected earnings and strong procedure growth guidance.

eBay Inc. (Nasdaq: EBAY) shares are up after beating quarterly expectations and guiding third-quarter revenue slightly higher.

SanDisk Corp. (Nasdaq: SNDK) shares are down after it beat Q2 expectations, but gave cautious guidance.

Qualcomm Inc. (Nasdaq: QCOM) shares are falling after it beat expectations, but only guided in-line, amid analyst concerns about average selling prices.

— The 24/7 Wall St. Team

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