X0303 4 2011-07-15 0 0001490892 CoreSite Realty Corp COR 0001423891 Thompson John David 1050 17TH STREET SUITE 800 DENVER CO 80265 1 0 0 0 Restricted Stock Unit 2011-07-15 4 A 0 37 0.00 A Common Stock 37 4975 D Each Restricted Stock Unit ("RSU") represents the right to receive one share of Common Stock. The reporting person also holds a tandem Dividend Equivalent ("DE") for each RSU held, which gives the reporting person the right to receive, upon the payment of any ordinary quarterly cash dividend paid to holders of Common Stock, an equivalent payment in the form of additional RSUs and DEs. The RSUs will vest on September 28, 2011, and thereafter will be payable upon the reporting person's termination of service as a director. The RSUs have no expiration date. /s/ Derek S. McCandless, attorney-in-fact 2011-07-18