Key Highlights

● Anthropic filed its S-1 on Monday, October 26, 2026.

● The filing was credited with early-week gains.

● The S&P 500 and Nasdaq later fell for the third straight week.

● First-half Revenue was $16.3 billion.

Wall Street opened the final week of October on a hopeful note. Anthropic, the San Francisco-based developer of the Claude AI models, filed its S-1 registration statement on Monday, October 26, 2026, for a listing on the Nasdaq Global Select Market under the ticker "ANT." market data credited the filing with helping drive early-week gains in the S&P 500 and the Nasdaq.

The filing gave investors a first look at the company's numbers: first-half 2026 revenue of $16.3 billion and a first-half net loss of $80.7 billion, about $72 billion of which is non-cash and tied to convertible notes, according to market data aggregation of coverage. The offering could raise up to $100 billion, and the company was valued at $965 billion in May.

How the week turned

The optimism did not last. The Federal Reserve held rates steady on Wednesday, October 28, but two officials dissented in favor of a hike, and markets continued to price in a December increase. That night, Alphabet (NASDAQ:GOOGL) reported results that missed on Earnings and showed free Cash Flow of negative $9.1 billion. Its shares had their worst day ever on Thursday, losing about $500 billion in market value.

Intel (NASDAQ:INTC) and Amazon (NASDAQ:AMZN) reported Thursday night. Intel warned of cash burn this year, and Amazon showed trailing 12-month free cash flow of negative $42.4 billion. On Friday, October 30, 2026, the S&P 500 fell 140.32 points to 7,580.07, the Dow Jones Industrial Average dropped 572.25 points to 51,770.31 and the Nasdaq Composite lost 747.73 points to 25,437.00. It was the Nasdaq's worst day since June 5.

For the full week, the S&P 500 lost 43.61 points, the Dow shed 444.85 points and the Nasdaq dropped 518.34 points, according to the Associated Press. Market data noted it was the third straight weekly decline for both the S&P 500 and the Nasdaq. Small caps bucked the trend, with the Russell 2000 gaining 35.95 points for the week despite a 47.37-point drop on Friday.

The swing from the early-week rally to Friday's rout shows how sensitive the market has become to news about AI. A filing that promised a new way to invest in the technology lifted stocks; earnings that showed how much the technology costs sent them tumbling.

What strategists said

A senior market strategist described the dynamic directly: "The love-hate relationship with tech and AI continues, and investors are becoming more discerning following earnings." A senior market analyst said that "Global markets are ending an exceptionally busy week on a cautious note" and that "strong AI Demand is no longer enough on its own."

A trading specialist said: "A lot of them kind of got ahead of themselves. It's all earnings based and right now, they're not producing."

A broader rotation

Not every part of the market fell. Energy, consumer staples, utilities and health care rose on Friday, and six of the 11 major sectors finished higher. Money moved out of AI, chips and megacap tech and into defensive areas, a shift that left the equal-weighted S&P 500 down far less than the cap-weighted index. Oil above $100 a barrel helped lift energy shares, with Exxon Mobil (NYSE:XOM) and Chevron (NYSE:CVX) briefly touching record highs.

What to watch

Anthropic's next step is a price range, and market reports said the market debut is targeted for the week of November 16. Before then, investors face Apple (NASDAQ:AAPL)'s results on Monday, November 2, the midterm elections on Tuesday, November 3, and the October jobs report on Friday, November 6. Whether the AI trade steadies in that stretch may determine whether the listing gets the same warm reception the filing did.