Investing.com -- Arm Holdings ADR stock fell 7.3% in morning trading Monday, reaching a session low of $283.72, as investors reduced positions following a disclosed insider sale and valuation concerns.

The decline follows CFO Jason Child's sale of 10,400 ordinary shares at $300 per share on September 21, a transaction valued at approximately $3.12 million. The sale was executed under a pre-arranged Rule 10b5-1 plan.

The stock has retreated from its 52-week high of $452.70 and currently trades near analyst consensus fair value estimates of approximately $287. The company's trailing and forward earnings multiples rank among the highest in the semiconductor sector.

A sharp rally on September 21, driven by investor interest in Meta's Muse AI agent and its potential impact on server-processor demand, has reversed as traders took profits. The stock has faced selling pressure from short-term momentum traders and institutional investors securing gains from the recent surge.