The major averages finished Thursday's session with a sharply divided performance as substantial selling pressure in technology and AI-related stocks overshadowed strength across much of the broader market. The S&P 500 (-1.2%) and Nasdaq Composite (-2.6%) suffered sizable losses, with both falling below their respective 50-day moving averages, while the DJIA (flat) recovered to finish near unchanged. The contrast was even more pronounced beneath the surface, as the S&P 500 Equal Weighted Index (+0.8%) registered a solid gain despite the decline in its market-cap-weighted counterpart.

The retreat marked a sharp reversal from Wednesday's technology-led advance, with the latest round of earnings reports renewing concerns about the costs and near-term growth prospects of the AI buildout. Investors have become increasingly focused on the substantial capital required to expand computing infrastructure, intensifying competition for financing, and supply chain constraints that could limit companies' ability to meet elevated growth expectations.

The information technology sector (-3.0%) was among the weakest performers, with the PHLX Semiconductor Index (-6.7%) suffering an especially steep decline. Lam Research (LRCX 230.15, -30.66, -11.76%) faced substantial selling pressure after its forward guidance highlighted supply chain constraints, adding to concerns about the semiconductor industry's ability to sustain its recent growth trajectory. The weakness extended to AI infrastructure companies such as CoreWeave (CRWV 55.60, -6.22, -10.06%), reflecting broader skepticism about the pace and financing of continued expansion.

The communication services sector (-3.0%) also struggled, weighed down by a disappointing earnings reaction in Meta Platforms (META 648.85, -48.67, -6.98%). The company reported stronger-than-expected revenue and underlying earnings, supported by continued advertising growth, but investors focused instead on the mounting costs of its AI investments. Quarterly capital expenditures exceeded operating cash flow, resulting in negative free cash flow, while underlying operating margins contracted from a year ago. Bloomberg also reported that a measure of Meta's credit risk reached a record high, underscoring concerns about the financing requirements associated with its expansion plans.

Tesla (TSLA 374.58, -11.89, -3.08%) also declined following its earnings report, contributing to weakness in the consumer discretionary sector (-1.7%). Although the company exceeded adjusted EPS expectations and reported improving automotive margins, declining operating income and a reduction in its FY26 capital expenditure outlook to approximately $20 billion from more than $25 billion raised questions about the pace of investment in its autonomous driving and robotics initiatives.

The selling extended beyond traditional technology companies, with the industrials sector (-0.9%) pressured by sharp declines in electrical equipment and power infrastructure names associated with the AI buildout, including GE Vernova (GEV 827.42, -98.50, -10.64%), Quanta Services (PWR 552.44, -48.70, -8.10%), Eaton (ETN 368.99, -24.95, -6.33%), and Bloom Energy (BE 217.77, -20.76, -8.70%).

However, the sector's losses were moderated by strength in transportation stocks following favorable earnings reports from Ryder System (R 265.53, +25.22, +10.49%) and others.

While the AI-related retreat weighed heavily on the major averages, investors continued to favor lower-beta and defensive stocks. The Vanguard Mega Cap Growth ETF (-2.8%) underperformed significantly, while gains in the consumer staples (+3.1%), utilities (+2.0%), health care (+1.3%), and financials (+1.2%) sectors helped support the broader market. The consumer staples sector led the advance, benefiting from a strong earnings reaction in Procter & Gamble (PG 165.59, +8.75, +5.58%) .

The health care sector also finished higher despite substantial weakness in Moderna (MRNA 202.63, -43.18, -17.57%), which plunged following reports that cancer vaccine data had partially leaked ahead of the European Society for Medical Oncology conference. Moderna and Merck (MRK 147.24, -2.64, -1.76%) subsequently disclosed Phase 3 melanoma results showing that their combination treatment reduced the risk of recurrence or death by 42% compared with KEYTRUDA alone, although overall survival data remain immature.

Participation outside the largest technology companies was considerably healthier than the headline index losses suggested. The Russell 2000 (+0.1%) eked out a gain, while the S&P Mid Cap 400 (-0.8%) posted a more moderate decline. The S&P 500 Equal Weighted Index's 0.8% advance further highlighted the extent to which weakness in a relatively concentrated group of influential growth stocks dictated the performance of the major averages.

Elsewhere, crude oil prices climbed amid heightened geopolitical concerns surrounding potential additional U.S. and Israeli strikes against Iran. WTI crude futures settled $2.29 higher (+2.4%) at $99.45 per barrel, adding another source of uncertainty for investors already contending with the reassessment of AI-related growth expectations. Treasury yields, meanwhile, fell sharply as safe-haven demand and short-covering supported government bonds. The 2-year note yield declined 17 basis points to 4.65%, while the 10-year note yield settled 19 basis points lower at 4.95%, falling below 5.00% for the first time since September 22.

Although lower yields helped support rate-sensitive and defensive stocks, they provided little relief to the technology companies at the center of the selloff. Today's session underscored the increasingly selective nature of the market's recent trading. The sharp retreat in AI-related stocks reflected mounting scrutiny of the costs and returns associated with the industry's expansion, but strength across defensive sectors, transportation stocks, and the equal-weighted S&P 500 indicated that buying interest remained intact elsewhere. With another batch of earnings reports due after the close, investors will have additional opportunities to assess whether the outlook for AI-related growth can justify the market's elevated expectations.

• Russell 2000: +12.2% YTD
• S&P 500: +12.0% YTD
• Nasdaq Composite: +11.9% YTD
• S&P Mid Cap 400: +10.0% YTD
• DJIA: +10.0% YTD

Reviewing today's data:

• Initial jobless claims were down 6,000 for the week ending October 17 to 194,000 (Briefing.com consensus: 200,000). Continuing jobless claims for the week ending October 10 increased by 25,000 to 1.728 million.
  
  • The key takeaway from the report is still the same. Layoff activity is low, which is consistent with a solid demand environment for goods and services.
• Sep Leading Economic Index 0.0% (Briefing.com consensus -0.2%; Prior -0.1%)
  10/17 EIA Natural Gas Inventories +77 bcf (Prior +67 bcf)