* Offering from shelf registration filed on Nov 25 last year

* Shares down 12 percent after the bell

July 7 (Reuters) - Arena Pharmaceuticals Inc (ARNA.O: Quote, Profile, Research) said it plans to offer common shares from a shelf registration filed with the U.S. Securities and Exchange Commission last year.

In the Nov 25 filing, the company said it would offer up to 25 million common shares at a maximum offering price of $3.27 apiece.

Arena shares fell over 12 percent to $4.10 in after-hours trade. They closed at $4.67 Tuesday on Nasdaq. (Reporting by Shailesh Kuber in Bangalore; Editing by Ratul Ray Chaudhuri)