Sept 6 (Reuters) - Atrium Mortgage Investment Corp AI.TO
* Atrium Mortgage Investment Corporation announces $25 million public offering of common shares
* Atrium Mortgage Investment Corp - Offering of common shares 2.1 million common shares of Atrium at a price of $11.85 per share
* Atrium Mortgage Investment Corp - Will use net proceeds of offering to repay existing indebtedness under its revolving operating credit facility