The Direxion Daily MU Bull 2X Shares (MUU), a leveraged exchange-traded fund tracking Micron Technology, plummeted 5.48% in after-hours trading on Monday. The sharp decline followed a significant rally in the prior session and highlights the heightened volatility in the memory chip sector.

The sell-off was triggered by a "sell the news" reaction following Samsung Electronics' stellar second-quarter results, which showed a staggering 19-fold year-on-year surge in operating profit driven by explosive AI memory chip demand. Despite the strong performance, market sentiment turned negative as investors grappled with broader concerns about intensifying competition, potential overcapacity in the semiconductor sector, and the sustainability of massive AI investments.

Adding to the pressure were bearish signals from renowned investor Michael Burry, who recently established a short position in Micron, warning that the stock's cyclical peak may have surpassed historical bubble levels. Furthermore, unresolved concerns over AI computing overcapacity—sparked by reports of Meta Platforms considering selling idle AI compute resources—continue to weigh on sentiment. Analysts also note that the core logic driving the memory chip rally—continuous upward revisions to earnings expectations—is losing momentum, shifting the focus to the actual delivery of results and raising questions about how long the sector's outperformance can last.