The amount will deliver gross proceeds of $126.8 million. The company expects net proceeds of $121 million.
On Tuesday, COPT originally said it would sell 2 million shares to fund development costs and other leasing activities, before increasing the offer to 3.25 million shares.
The company expects the offering to close Sept. 29 and said it will use the proceeds to repay debt.
COPT stock increased 36 cents, or 0.9 percent, to close at $39.56 per share Thursday.