05:24 PM EDT, 06/23/2025 (MT Newswires) -- Alamos Gold ( AGI ) edged lower in after-hours New York trade as the company after close of trade Monday released details of a new life of mine(LOM) plan for its Island Gold District in Ontario.

According to a company statement, the Base Case LOM Plan integrates Island Gold and Magino as one consolidated long-life operation that is expected to become "one of the largest, lowest-cost, and most profitable gold mines in Canada."

Highlights from the plan show an average annual gold production of 411,000 ounces starting in 2026 and over the initial 12 years, and a 43% increase from the mid-point of 2025 production guidance driven by the completion of the Phase 3+ expansion.

It is expected that there will be an "average annual production of 306,000 ounces" over the 20-year mineral reserve life.

The company also said it expects all-in sustaining costs of US$1,033 per ounce over the 12-year plan, 11% below its 2025 guidance.

"This is a first look at an operation with significant upside potential which we expect to detail in an Expansion Study later this year," said chief executive John McCluskey. "We expect this to include a larger mineral reserve through ongoing mineral resource conversion, and a potential further expansion up to 20,000 tonnes per day, supporting an even larger, more valuable, and profitable operation."

The company's shares were last seen down US$0.21 to US$26.53 after hours. They closed up $0.38 to $36.74 on the Toronto Stock Exchange.