The news of Alcoa engaging with potential buyers for its San Cibrao facility indicates a strategic move that could potentially streamline its operations and focus on more profitable ventures. The proposal to modify the viability agreement suggests an effort to make the asset more attractive to buyers or to improve operational efficiencies. This development is likely to be viewed positively by investors, as it demonstrates proactive management and could lead to financial gains or cost savings in the long term. However, the impact on the stock price in the short term will depend on further details about the potential sale and the terms of the modified viability agreement.