Shares of Sigma Lithium fell after the lithium producer said a preliminary judicial ruling in Brazil purported to suspend its environmental licenses, though it vowed to fight the ruling.

Shares were down 15% to $10.54 as of Tuesday afternoon. The stock has fallen 20% this year.

Sigma Lithium said its mining and industrial activities continue to operate, adding that it had not received any legal communication about the preliminary ruling. It said the ruling was reportedly issued during a recess of Brazilian courts without following due process.

"The Company believes this ruling is unwarranted and in dissonance with Brazil's strong rule of law, as due process has not been followed," it said on Monday, adding that it planned to begin its legal defense when courts reopen on Tuesday.

The company also "vehemently" objected to media reports that the ruling would overrule an agreement with the Minas Gerais State Authorities, though it said "the frequency of inaccurate news reports about its business could increase" ahead of a contested Brazilian general election.

"Sigma Lithium remains focused on scaling up its mining operations to advance its expansion plans and expecting to deliver 240,000 tonnes of lithium oxide concentrate within 12 months and 330,000 tonnes in FY 27," the company said.

The preliminary ruling includes a provision for a daily fine that would be due in the event of a final negative ruling, as well as other provisions that would also take effect only once the full legal process has been completed, possibly in multiple years, the company said.