X0306 4 2013-12-16 0 0001178670 ALNYLAM PHARMACEUTICALS, INC. ALNY 0001458494 Vaishnaw Akshay 300 THIRD STREET CAMBRIDGE MA 02139 0 1 0 0 EVP, Chief Medical Officer Common Stock 2013-12-16 4 M 0 3750 9.14 A 16338 D Common Stock 2013-12-16 4 M 0 6250 9.3 A 22588 D Common Stock 2013-12-16 4 M 0 5000 7.1 A 27588 D Common Stock 2013-12-16 4 S 0 10744 60.1851 D 16844 D Common Stock 2013-12-16 4 S 0 4256 60.7776 D 12588 D Common Stock 2013-12-17 4 M 0 18480 12.96 A 31068 D Common Stock 2013-12-17 4 S 0 8500 60.5881 D 22568 D Common Stock 2013-12-17 4 S 0 9980 61.399 D 12588 D Common Stock 2615 I by Managed Account Stock Option (right to buy) 7.1 2013-12-16 4 M 0 5000 0 D 2021-11-30 Common Stock 5000 20000 D Stock Option (right to buy) 9.14 2013-12-16 4 M 0 3750 0 D 2020-12-08 Common Stock 3750 7500 D Stock Option (right to buy) 9.3 2013-12-16 4 M 0 6250 0 D 2021-06-09 Common Stock 6250 37500 D Stock Option (right to buy) 12.96 2013-12-17 4 M 0 18480 0 D 2016-01-02 Common Stock 18480 22145 D Stock Option (right to buy) 63 2013-12-18 4 A 0 32500 0 A 2023-12-18 Common Stock 32500 32500 D The sales reported on this Form 4 were made pursuant to a Rule 10b5-1 trading plan. Sale prices ranged from $59.61 to $60.54. Sale prices ranged from $60.62 to $61.29. Sale prices ranged from $59.99 to $60.98. Sale prices ranged from $60.99 to $61.96. The reporting person owns 2,615 shares of ALNY common stock under the ALNY 401(k) plan as a result of the ALNY 401(k) matching contribution program. The stock option vests as to 25% of the shares on the 1st anniversary of the date of the stock option grant and as to an additional 6.25% of the shares each successive three month period thereafter. /s/ Michael P. Mason, Attorney-in-Fact for Akshay K. Vaishnaw 2013-12-18