Coherent Corp. (COHR) closed at $266.49 on September 15, 2026, down 12.71% from the prior session. The single-day loss was among the steepest recorded for the photonics and compound semiconductors company in recent memory, pushing its market capitalization to $59.8 billion.
The decline extends a broader downtrend for the stock. Over the past seven days, COHR has shed 5.48%, while the 30-day loss now stands at 18.22%, reflecting sustained selling pressure across that period.
The combination of a double-digit single-day drop and a deepening monthly loss signals that the stock has faced consistent headwinds over multiple timeframes. At the current price of $266.49, shares sit markedly below where they traded a month ago.
No specific corporate announcements were cited in the available data to account for Tuesday's move. The figures reflect closing market activity as of September 15, 2026.
