** Shares of Semiconductor supplier Semtech SMTC.O slumps 25.1% premarket to $40.81

** Co's stock lost nearly 10% on Friday

** SMTC in its 8-K filing says FY26 net sales from its CopperEdge products expected to be lower than previous forecasts of $50 mln

** SMTC lowers forecasts due to rack architecture changes, with no expected ramp-up over the course of fiscal year 2026

** Brokerage Piper Sandler cuts PT to $55 from $75 after the filing, says "we recognize a setback here"

** "Primary reason for our estimate reduction is due to a change of rack architecture at Nvidia, which reduces our forecast around SMTC's active copper cable (ACC) opportunity" - Piper Sandler

** SMTC gained 182.3% in 2024 and is down 11.9% YTD

(Reporting by Pranav Kashyap in Bangalore)

((Pranav.Kashyap@thomsonreuters.com; +919886482111;))