Diamondback Energy is trading 7.33% lower at $189.48 in pre-market; no verified company-specific announcement explaining the drop surfaced in the available search. - The stock closed at $204.48 on October 27. - The EPA’s proposed methane-rule rollback is relevant industry news, but available reporting does not link it directly to the decline. - Supplied broad-index indications are mixed and do not provide a clear explanation.