X0203 3 2009-11-16 0 0000879407 ARROWHEAD RESEARCH CORP ARWR 0001486672 Myszkowski Kenneth Allen ARROWHEAD RESEARCH CORPORATION 201 S. LAKE AVE., SUITE 703 PASADENA CA 91101 0 1 0 0 CFO Stock Option 0.70 2010-05-16 2019-11-16 Common Stock 250000 D Stock Option 0.52 2010-04-01 2020-03-04 Common Stock 80000 D Vesting of 125,000 shares begins on May 16, 2010, at which time 15,632 shares vest; the balance vests on the first of each month thereafter in equal monthly installments of 2,604 shares. Vesting of the remaining 125,000 shares begins on August 1, 2010, at which time 15,632 shares vest; the balance vests on the first of each month thereafter in equal monthly installments of 2,604 shares. Vesting in 24 equal monthly installments beginning on 4/01/10. Kenneth Allen Myszkowski 2010-04-12