 Shares of Sylvamo Corp. SLVM, -4.61 sank 5.1 in premarket trading Wednesday, after the Tennessee-based paper company said it may curtail or temporarily shut down production at its mill in Svetogorsk, Russia later this week, because it is facing inadequate supplies of critical raw materials. The company said the Svetogorsk mill, which is located at the Finland border, has about 1,700 employees, and has an annual capacity of 720,000 short tons of pulp, paper and paperboard. 