Sigma Lithium Corp. is plunging amid growing doubts about near-term production and potential delays to a key expansion project.
In a sharp reversal for a stock once seen as an industry darling, Sigma has lost almost one-third of its market value this week for the worst two-day slump in 21 months. On Tuesday, the stock was down more than 7%, making it one of the worst performers in an index of lithium producers.
Late Monday, BMO Capital Markets joined a growing chorus of analysts tempering outlooks after Sigma abruptly changed mining contractors last month as part of measures the company said were aimed at improving efficiency at its flagship Brazilian mine.
Plans to begin using larger trucks and modernize some gear may inflate capital-spending requirements and slow an expansion project, analysts said.
“We’re not sure of the exact reason for recent volatility in the stock but know there are…
