Key Highlights

  • Coherent (NYSE:COHR) rose 16.79% to USD 225.19 on November 9, 2026, the largest gain in the S&P 500, as optical networking stocks rallied.
  • Monolithic Power Systems gained 16.60% to USD 1,388.05, Astera Labs rose 13.72% and MaxLinear climbed 13.68% in a broad semiconductor rebound.
  • AMD rose 13.26% to USD 508.58 after a brokerage upgrade to outperform with a USD 600 price target, citing data centre growth.
  • The semiconductor index gained 6.9%, its best day since July 30, while First Solar, Nvidia and Take-Two Interactive were among the decliners.

Optical Names Led the Charge

Coherent (NYSE:COHR) makes lasers, optical transceivers and materials used to move data between servers inside AI data centres, where Demand for faster connections has grown rapidly. The stock had been hit hard in the selloff that followed the midterm elections, when fears about restrictions on new data centres drove the semiconductor index down more than 12% in one session on November 5, 2026. On November 9, the whole optical group recovered, with two other optical suppliers each rising about 10.7%. The move reflected a sector-wide bid rather than company-specific news, as investors concluded that the selloff had gone too far for suppliers with strong order books. Optical components are a direct beneficiary of AI cluster growth, because each new generation of accelerators needs more bandwidth, so the group tends to move sharply in both directions as sentiment on AI Capital spending changes. Coherent also supplies industrial lasers and materials, which gives it some Diversification beyond data centres.

Analog, Connectivity and AMD

Monolithic Power Systems, which supplies power management chips for AI servers, rose 16.60% to USD 1,388.05 alongside a broad bid for analog semiconductor stocks, with no confirmed company catalyst. Astera Labs, which makes connectivity chips that link processors and memory, gained 13.72%, and MaxLinear rose 13.68%. AMD added 13.26% to USD 508.58 after a brokerage upgraded the stock to outperform with a USD 600 target, about 18% above the close, arguing that data centre Revenue could grow about 135% by 2027 and make up most of sales, with demand from major AI developers. The breadth of the move across connectivity, power and compute shows that investors were rebuilding exposure to the whole AI hardware chain rather than a single theme after the prior week's rout, a pattern typical of sharp relief rallies.

Losers and What Comes Next

Not every name joined in. First Solar fell 4.74% to USD 191.61 after a price target cut, Nvidia dropped 4.27% after its board opened an investigation involving its chief executive, and Take-Two Interactive fell 3.48% to USD 207.40 ahead of its quarterly report. For Coherent (NYSE:COHR) and the other leaders, a single strong day does not remove the risks that triggered the selloff. Local and state limits on data centre construction could slow new capacity, and higher interest rates could make it harder for AI companies to finance their buildouts. Valuations are also elevated after strong gains earlier in the year, which leaves the group vulnerable to any disappointment in orders or guidance. Investors will look to Nvidia's Earnings on November 17, any updates on data centre permitting and order commentary from optical and networking suppliers to judge whether the rebound can be sustained into year end.

Where Things Stand

Coherent led the S&P 500 with a 16.79% gain on November 9, 2026, followed by Monolithic Power at 16.60%, Astera Labs at 13.72%, MaxLinear at 13.68% and AMD at 13.26%, as AI hardware stocks rebounded and the semiconductor index rose 6.9%. Most gains reflected a sector-wide bid rather than company news. Data centre permitting and Nvidia's November 17 results are the next tests.