X0306 4 2020-06-12 0 0001080709 ARENA PHARMACEUTICALS INC ARNA 0001768011 Knobil Katharine C/O ARENA PHARMACEUTICALS, INC. 6154 NANCY RIDGE DRIVE SAN DIEGO CA 92121 1 0 0 0 Common Stock 2020-06-12 4 A 0 1223 0.00 A 1308 D Common Stock 2020-06-12 4 A 0 2446 0.00 A 3754 D Stock Option (right to buy) 61.31 2020-06-12 4 A 0 2500 0.00 A 2027-06-12 Common Stock 2500 2500 D Stock Option (right to buy) 61.31 2020-06-12 4 A 0 5000 0.00 A 2027-06-12 Common Stock 5000 5000 D The amount represents restricted stock units that vest in three equal installments on the dates of Arena's next three annual meetings of stockholders. The shares underlying the restricted stock units will be issued upon vesting and release of the restricted stock units. The amount represents restricted stock units that vest in full on the earliest of June 12, 2021, or the date of Arena's next annual meeting of stockholders. The shares underlying the restricted stock units will be issued upon vesting and release of the restricted stock units. The options vest in 36 equal monthly installments (except as otherwise necessary to avoid vesting of a fractional share) over three years beginning on July 12, 2020, and are exercisable once vested. The options vest in 12 equal monthly installments (except as otherwise necessary to avoid vesting of a fractional share) over one year beginning on July 12, 2020, and are exercisable once vested. /s/ Andrew J. Cronauer, as Attorney-in-Fact 2020-06-16