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Portola Pharmaceuticals falls on stock offering

SOUTH SAN FRANCISCO, Calif. (AP) -- Shares of Portola Pharmaceuticals Inc. fell Wednesday after it said that it plans to raise about $100 million through a public offering of 4.8 million shares, just five months after the stock debuted.

The pharmaceutical company, which is based in South San Francisco, Calif., develops treatments for blood clotting and inflammation. It held its initial public offering in May.

Portola said that it plans to sell about 4.5 million of its shares. Existing shareholders are selling another 342,290 shares. Most of that is being sold by Brookside Capital Partners Fund, which is an affiliate of private equity firm Bain Capital that currently holds about 6.2 percent of Portola's outstanding shares, according to FactSet.

The shares will be priced at $22.12. That's a 3 percent discount to the stock's Tuesday closing price of $22.83.

Portola plans to use the money raised to research and develop its treatments.

Shares of the company fell 99 cents, or 4.3 percent, to $21.84 in midday trading. The stock dropped as much as 9 percent earlier in the session.