Arrowhead Research Corp. on Monday said it entered into a securities purchase agreement with institutional and individual investors to raise gross proceeds of about $6.2 million.

Participants include several existing investors of the Pasadena biotech plus a new fund dedicated to health care investments. The placement included 2.3 million shares of common stock and warrants to purchase an additional 1.7 million shares.

The warrants have an exercise price of $3.25 with a term of four years from the date of issuance.

Shares closed down 46 cents, or 14 percent, to $2.79 on the Nasdaq.