MKS shares fall 5.49% after hours as Citi lowers price target to $290 and valuation concerns emerge.

MKS Instruments (MKSI) fell 5.49% in after-hours trading following analyst revisions that signaled caution. Citi analysts Atif Malik and Elizabeth Sun lowered the firm’s price target to $290 from $295, maintaining a “Buy” rating but reflecting tempered optimism. This adjustment, combined with broader valuation concerns—such as MKS trading below a calculated fair value of $281.25 and a current 54x P/E ratio exceeding industry averages—suggested waning confidence in near-term growth prospects. The move aligns with recent market cooling, as MKS’s 30-day share price had already declined 9.9% after a strong 12-month rally. While analysts highlighted risks like AI demand volatility and debt reduction challenges, the direct trigger for the after-hours selloff was the downward revision of expectations by key analysts.