Monolithic Power Systems (MPWR) Stock After the Bell: Nasdaq-100 Debut, Key Drivers, and What to Watch Before the Dec. 23 Open
Monolithic Power Systems, Inc. (NASDAQ: MPWR) finished Monday’s session (December 22, 2025) modestly higher, closing at $945.16—up 0.86% on the day—after a notably volatile intraday swing that saw the stock trade as high as $976.05 and as low as $937.10. As of early evening trading, after-hours action was essentially flat, with the stock still quoted at $945.16 around 6:15 p.m. ET. StockAnalysis The headline context behind MPWR’s Monday spotlight: its addition to the Nasdaq-100 became effective prior to today’s market open, a structural catalyst that can reshape short-term flows, liquidity, and investor attention—especially during a holiday-shortened week when trading conditions