Osisko Mining Inc. Decrease Equity Interest in IDM Mining Ltd.

TORONTO, ONTARIO--(Marketwired - Oct 25, 2016) - Osisko Mining Inc. (TSX:OSK) (the "Corporation") announces that, through a series of trades ending on October 25, 2016, it disposed of an aggregate of 1,281,000 common shares of IDM Mining Ltd. ("IDM Mining") through the facilities of the TSX Venture Exchange at an average price of approximately $0.197 per share for total consideration of $252,295.00 (the "Transactions").

Before giving effect to the Transactions, the Corporation had ownership or control, directly or indirectly, over an aggregate of 25,992,944 common shares of IDM Mining, representing approximately 11.8% of the issued and outstanding common shares of IDM Mining on a non-diluted basis, and approximately 14.5% of the issued and outstanding common shares of IDM Mining on a partially-diluted basis (assuming the exercise in full of the 6,972,222 common share purchase warrants of IDM Mining held by the Corporation). After giving effect to the Transactions, the Corporation had ownership or control, directly or indirectly, over an aggregate of 24,711,944 common shares of IDM Mining, representing approximately 8.9% of the issued and outstanding common shares of IDM Mining on a non-diluted basis, and approximately 11.1% of the issued and outstanding common shares of IDM Mining on a partially-diluted basis (assuming the exercise in full of the 6,972,222 common share purchase warrants of IDM Mining held by the Corporation).

The Corporation reviews its holdings from time to time and may increase or decrease its position as future circumstances may dictate. The Corporation, after reviewing market and other conditions, decreased its holdings in IDM Mining pursuant to Transactions.

This news release is being issued in accordance with National Instrument 62-103 - The Early Warning System and Related Take-Over Bid and Insider Reporting Issues in connection with the filing of an early warning report dated October 25, 2016. The early warning report respecting the Transactions has been filed on System for Electronic Document Analysis and Review ("SEDAR") at www.sedar.com under IDM Mining's issuer profile. To obtain a copy of the early warning report filed by the Corporation, please contact John Burzynski at (416) 363-8653 or refer to the SEDAR at www.sedar.com under IDM Mining's issuer profile.

The Corporation's head office is located at 155 University Avenue, Suite 1440, Toronto, Ontario M5H 3B7.

Contact

John Burzynski
President & Chief Executive Officer
(416) 363-8653