Option Care ( OPTN) skyrocketed Monday on merger news as a few other health stocks recorded smaller gains from scattered news during a flat-to-green session.

Walgreen ( WAG) will pay $19.50 a share, or some $850 million total, for Option Care, a specialty pharmacy-services company based in Buffalo Grove, Ill. Option Care bolted $3.84, or 25%, to $19.24. Walgreen was up 17 cents, or 0.4%, to $43.70.

Small-cap bio-nanotech company pSivida ( PSDV) took off in the opposite direction after announcing that it entered an agreement for a direct offering to sell its Nasdaq-traded American Depositary Shares and warrants to purchase ADSs, including $6.5 million, to Pfizer ( PFE).

It estimates the net proceeds from the offering will be $16.3 million after the placement agent fees and estimated offering expenses. Shares of pSivida were down 32 cents, or 21%, to $1.20.

A few other companies had smaller moves to start the week.

San Francisco-based biopharmaceutical company Anesiva ( ANSV) said Monday that preliminary follow-up data from a phase II study show that osteoarthritis treatment Adlea reduced knee pain for up to 12 weeks and continued to be well-tolerated. The company said it's on track to advance Adlea to a phase II/III trial for osteoarthritis of the knee in addition to late-stage trials in various indications this summer. Anesiva rose 35 cents, or 5.7%, to $6.50.

Also up, Spectranetics ( SPNC) said it received clearance from the Food and Drug Administration to market its Turbo-Booster catheter to treat arterial stenoses and occlusions, or narrowing or closing of arteries and blood vessels, in the leg. The stock was up 69 cents, or 6%, to $12.21.

Upon selling 22 underperforming assets to Kindred Healthcare ( KND) for $171.5 million, health-care real estate investment trust Ventas ( VTR) rose $1.20, or 3.3%, to $37.44. Ventas expects to record a gain of $129 million in the second quarter from the sale of the properties it previously leased to Kindred. Health-care services company Kindred moved 10 cents, or 0.3%, to $30.82.

The Nasdaq Biotechnology Index was up 6.13, or 0.8%, to 808.81. One more winner, a component of the index, Acorda Therapeutics ( ACOR) said Monday that it joined the Russell 3000 Index as of June 22. The stock benefited 90 cents, or 5.3%, to $17.96.

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