Key Highlights

  • The S&P 500 rose 0.70% to 7,676.77 on October 26, 2026 and the Nasdaq Composite 0.82% to 26,169.38, so holders of SPDR S&P 500 ETF Trust (NYSEARCA:SPY) and Invesco QQQ Trust saw a broad AI-led advance.
  • The Philadelphia Semiconductor Index rose 2.82% to 11,083.47 with all 30 members higher, the benchmark reading for holders of iShares Semiconductor ETF (NASDAQ:SOXX) in published market data on the dates cited.
  • SpaceX (NASDAQ:SPCX) fell 15% in its first week in the Nasdaq-100, a precedent for index-driven volatility that Anthropic's debut will test in published market data on the dates cited, according to the information reviewed.
  • Anthropic's pricing is expected around mid-November, and index buying could follow, which would affect Invesco QQQ Trust (NASDAQ:QQQ) first because of its Nasdaq-100 link in published market data on the dates cited.

SPDR S&P 500 ETF Trust (NYSEARCA:SPY): Tracking the S&P 500 Up 0.70%

Anthropic made its S-1 public at 9:00 a.m. ET on October 26, 2026, and the market liked what it read. The filing showed revenue of USD 16.3 billion in the first half of 2026 and a first operating profit of USD 974 million in Q2. Semiconductor stocks, which had been in correction, rose 2.82%. The Dow's smaller 0.28% gain compared with the Nasdaq Composite's 0.82% shows that technology led. SPDR S&P 500 ETF Trust (NYSEARCA:SPY) holds the index constituents in index weights, so the largest technology companies carried much of the return, and the fund's own price move is not stated here. The Nasdaq-heavy tilt of the day also explains why the Dow lagged. The S&P 500 is weighted by market value, so a handful of very large companies can lift it even when many shares do not rise. Morgan Stanley strategists see semiconductors another 10% to 15% lower before they stabilise around mid-November, which means one strong day does not settle the debate. The first-half net loss of USD 80.7 billion disclosed by Anthropic was mostly a non-cash charge of about USD 72.4 billion, which shows how headline numbers can mislead. Investors in SPDR S&P 500 ETF Trust (NYSEARCA:SPY) should compare gains in the leaders with participation across the other constituents.

Invesco QQQ Trust (NASDAQ:QQQ): Facing a Possible Nasdaq-100 Addition

The S-1 became public on October 26, 2026, pricing is expected around mid-November, and the roadshow is expected from the week of November 9. Published expectations say Anthropic could join the Nasdaq-100 within weeks of listing under a fast-entry approach, though the exact rule, date and weight were not verified here and Nasdaq will publish the details. Invesco QQQ Trust (NASDAQ:QQQ) tracks the Nasdaq-100, so any addition would require the fund to buy shares. The valuation talk of USD 1.5 trillion to more than USD 2 trillion matters, because float, the shares available to the public, will set the weight. Until Nasdaq confirms the rule, the timing should be treated as an expectation. A fund holder should also note that inclusion does not mean the stock will rise. Funds that track an index must hold each member in the index's proportion, so an addition forces buying, often concentrated around the effective date. After that demand is complete, support can fade, and the fall of 15% in SpaceX in its first week in the Nasdaq-100 is the precedent cited. Anthropic's staggered lock-up adds supply on days 1, 27, 48, 62 and 76 after listing, which is more supply, sooner, than in a standard 180-day lock-up. A control structure with a Class F share giving founders 50.1% of votes also limits the influence of public holders of Invesco QQQ Trust (NASDAQ:QQQ).

iShares Semiconductor ETF (NASDAQ:SOXX): Following Chips Up 2.82%

On October 26, 2026 the Philadelphia Semiconductor Index gained 2.82% to 11,083.47, with all 30 members higher. The S&P 500 rose 0.70% and the Nasdaq Composite 0.82% in what was Wall Street's best day in a month. iShares Semiconductor ETF (NASDAQ:SOXX) holds semiconductor shares, so the index move is the benchmark reading for the fund, but no separate fund price move is stated here. The index extended its rise on October 27, 2026, gaining 3.60% to 11,482.51 in published market data. Two sessions of gains are a recovery from a correction, not proof that the correction has ended. The index figures are published market data, and a gain this broad shows buyers across designers, equipment makers and memory suppliers. Anthropic's S-1 shows about USD 637 billion of named compute contracts, of which about USD 430 billion cannot be cancelled. Compute needs processors, networking and memory, so a buyer committing to years of capacity supports demand across the supply chain. Anthropic's revenue rose from USD 4.73 billion in Q1 2026 to USD 11.56 billion in Q2, with Q3 unaudited at USD 16.8 billion, which shows the demand is being monetised. A fund such as iShares Semiconductor ETF (NASDAQ:SOXX) is diversified across chip names but still moves with the sector's cycle, and no forecast is offered.

SpaceX (NASDAQ:SPCX): The 15% First-Week Precedent

SpaceX (NASDAQ:SPCX) listed in June 2026 at USD 1.77 trillion, raising USD 86 billion in a deal of USD 75 billion plus the greenshoe, the extra shares sold to cover over-allotment. After joining the Nasdaq-100 it fell 15% in its first week, according to analysis in the S-1 commentary. The mechanism is simple: funds that track an index must buy the new member, often just before inclusion, and after the buying is done the support disappears. Large lock-up releases add supply. The fall is a precedent for Anthropic's debut, not a rule, and one comparison cannot predict another. Unlike an ordinary IPO, the IPO was followed by quick index inclusion, which concentrated the buying into a short window. Anthropic's S-1 sets pricing around mid-November and shows about USD 430 billion of non-cancellable compute commitments. Reports of the filing say Anthropic committed up to USD 120.5 billion of compute spending through 2029, with SpaceX supplying capacity worth about USD 3.1 billion a month, but those figures come from reports and have not been confirmed from the filing here. SpaceX rose 1.14% to USD 148.58 on October 27, 2026. The Federal Reserve decision on October 28, 2026 and Microsoft and Alphabet earnings that evening can move AI sentiment, and so SpaceX (NASDAQ:SPCX).

Where Things Stand

The answer is that holders face a strong relief rally with real risks behind it: Morgan Stanley strategists expect chips to fall another 10% to 15% before stabilising, Anthropic's lock-up adds supply and index buying can fade after inclusion. SPDR S&P 500 ETF Trust (NYSEARCA:SPY) gained with the S&P 500, iShares Semiconductor ETF followed chips, Invesco QQQ Trust faces Nasdaq-100 changes and SpaceX shows the precedent. The evidence is positive for sentiment and mixed for risk. The Federal Reserve decision on October 28, 2026 is the next test. Further disclosure from Invesco QQQ Trust (NASDAQ:QQQ) would clarify the picture.