Sean Roosen

Sean Roosen
Nationality	Canadian
Occupation	Mining executive, entrepreneur
Title	Executive Chair
Employer	Osisko Mining Inc.
Known for	Co-founding Osisko Mining Corporation and developing the Canadian Malartic gold mine in Quebec

Sean Roosen is a Canadian mining executive best known for co-founding Osisko Mining Corporation and steering the development of the Canadian Malartic gold mine in Quebec, one of the largest open-pit gold mines in Canada. When Osisko Mining Corporation was acquired by Yamana Gold and Agnico Eagle Mines in 2014 in a transaction valued at approximately C$3.9 billion, the deal stood as one of the most significant gold mining takeovers in Canadian history to that point. Roosen subsequently co-founded a successor enterprise, Osisko Mining Inc., and built an interconnected group of Osisko-branded royalty and exploration companies. Across more than two decades in the mining industry, he has operated principally in Quebec and the broader Canadian Shield, pursuing gold discoveries at a time when junior mining development in Canada has become increasingly tied to questions of permitting timelines, Indigenous consultation, and community relations.

Early Life

Roosen grew up in Canada and pursued a career in the resource sector from an early stage. Detailed biographical information about his upbringing and family background has not been extensively documented in public sources. His professional identity has been shaped almost entirely by his work in the Quebec mining corridor, and his public record begins meaningfully with his involvement in building Osisko Mining Corporation in the early 2000s.

Career

Founding of Osisko Mining Corporation

Roosen co-founded Osisko Mining Corporation alongside Robert Wares and other partners in 2003. The company was incorporated under Canadian corporate law and listed on the Toronto Stock Exchange, focusing exploration activity on the Abitibi Greenstone Belt in Quebec, a geological formation historically associated with significant gold production.

The company's central project was the Canadian Malartic deposit, located near the town of Malartic in the Abitibi region of Quebec. Roosen served as President and Chief Executive Officer of Osisko Mining Corporation as the company advanced the project from exploration-stage discovery through feasibility study, permitting, and construction. Canadian Malartic presented an unusual set of challenges because the open-pit mine footprint required the relocation of a portion of the town of Malartic itself, including residential properties, a school, and community infrastructure. The relocation program became one of the most closely watched community engagement processes in Canadian mining during that period.

Development of Canadian Malartic

Construction of the Canadian Malartic mine began in 2009 following receipt of provincial environmental approval from the Quebec government. The mine entered commercial production in 2011. At full operation, Canadian Malartic processed approximately 55,000 tonnes of ore per day, making it one of the highest-throughput gold operations in Canada.

The project required capital investment of more than C$1 billion to build. Financing a development of that scale as a junior mining company on the Toronto Stock Exchange demanded repeated equity raises and debt financing arrangements. Roosen and the Osisko management team navigated a period of significant commodity price volatility, completing construction during years when gold prices rose sharply before beginning a prolonged correction after 2011.

The mine's production profile and reserve base made Osisko Mining Corporation an attractive acquisition target. Beginning in early 2014, Goldcorp launched a hostile takeover bid for Osisko that the Osisko board, under Roosen's leadership, rejected as inadequate. The board pursued an alternative transaction, ultimately agreeing to a joint acquisition by Yamana Gold and Agnico Eagle Mines, which the two bidders structured as a partnership to divide ownership of the mine equally. Osisko shareholders voted to approve the C$3.9 billion offer in June 2014. The transaction closed later that summer and effectively wound down Osisko Mining Corporation as an independent public company.

Osisko Gold Royalties

As part of the terms negotiated during the 2014 takeover defense, Osisko Mining Corporation spun out a royalty company called Osisko Gold Royalties Ltd., which held a 5 percent net smelter return royalty on the Canadian Malartic mine as its cornerstone asset. Roosen was involved in the formation of this entity, which began trading on the Toronto Stock Exchange and the New York Stock Exchange following the closing of the main transaction. Osisko Gold Royalties subsequently grew through acquisitions into one of the larger royalty and streaming companies listed in Canada.

Co-Founding Osisko Mining Inc.

Following the conclusion of the 2014 transaction, Roosen turned to building a new exploration and development company. Osisko Mining Inc. was incorporated and listed on the Toronto Stock Exchange, focused on gold exploration in Quebec and the Canadian Shield. Roosen assumed the role of Executive Chair. The company assembled a portfolio of properties in the Windfall Lake area of Quebec, where drilling results attracted sustained attention from institutional investors and sector analysts.

The Windfall gold project, located in the Urban-Barry greenstone belt of Quebec, became the flagship asset of Osisko Mining Inc. The project accumulated a substantial mineral resource estimate through extensive drilling programs conducted over multiple years. Roosen guided the company's strategy of systematic step-out and infill drilling to expand and define the deposit more precisely. Quebec's mining regulatory framework, including the provisions of the Mining Act administered by the Ministere des Ressources naturelles et des Forets, governed the permitting process for any potential future development at Windfall.

Transaction with Gold Fields

In 2023, Gold Fields Ltd., a South African gold mining company, announced a transaction to acquire Osisko Mining Inc. in a deal that valued the company's shares at approximately C$4.90 per share, representing a significant premium to the pre-announcement trading price. The proposed acquisition attracted regulatory and shareholder attention given the strategic importance of the Windfall project to Quebec's gold sector and the continuing involvement of the Canadian government in evaluating foreign acquisitions of resource assets under the Investment Canada Act. The transaction represented a further validation of the exploration work conducted under Roosen's leadership at Windfall. Roosen remained involved with the Osisko group of companies in his capacity as Executive Chair through the period of that transaction process.

The Osisko Group of Companies

Over time, the Osisko name became associated with a cluster of related but legally distinct entities operating across the mining value chain. In addition to Osisko Mining Inc. and Osisko Gold Royalties Ltd., associated companies included Osisko Development Corp., which focused on development-stage assets, and various other project-level vehicles. Roosen maintained a central role in the architecture of these entities, serving on boards and in executive capacities across several of them.

The structure reflected a broader strategy in the Canadian junior mining sector of separating royalty income streams from exploration risk, allowing investors to choose their level of exposure to the commodity cycle. Osisko Gold Royalties grew its portfolio aggressively through acquisitions during years when gold royalty companies commanded premium valuations relative to operating miners. Roosen's role in creating the original royalty through the 2014 takeover defense gave him particular credibility in articulating that strategy to institutional investors.

Industry Role and Advocacy

Roosen has spoken at mining industry conferences and in media interviews about the challenges of developing large gold projects in Canada, including permitting timelines, community relations, and access to capital for junior developers. He has commented publicly on Quebec's position as a favorable mining jurisdiction within Canada, citing the province's developed mining infrastructure, trained workforce, and hydroelectric power supply as competitive advantages for gold projects.

Canada's Critical Minerals Strategy, released by the federal government in 2022, identified gold alongside battery metals as a resource category where Canadian production capacity has strategic and economic importance. Roosen's career has been conducted almost entirely in the gold sector, with Windfall representing a project type that regulators and industry groups have cited as an example of new gold resource development in established Canadian mining provinces.

Recognition

Roosen has been profiled in the Northern Miner and other Canadian mining trade publications in connection with Osisko's successive exploration and development milestones. The successful defense of Osisko Mining Corporation against the 2014 Goldcorp hostile bid and the resulting C$3.9 billion transaction drew coverage from major Canadian business publications including the Financial Post and the Globe and Mail, which noted the outcome as an example of an effective hostile takeover defense in the Canadian resource sector.

The subsequent creation of Osisko Gold Royalties as a spinout from the takeover process was noted in industry commentary as an unusually favorable outcome for shareholders of the target company, given that the royalty stream provided ongoing income exposure to Canadian Malartic production after the sale of the operating mine itself.