The bull market turns four on Monday, and AI is the engine
The S&P 500 is near records ahead of October 12. Here is what the milestone does and does not tell you.
Markets · Friday, October 9, 2026 · 10:15 AM ET
The S&P 500 bull market reaches its fourth anniversary on Monday, October 12. That date marks four years since the index's closing low for this cycle, 3,577.03 on October 12, 2022, according to Yahoo Finance's account of Motley Fool research. The index closed at a record 7,818.93 on October 6.
How big the gain is
Reuters puts the run's gain at 117%. Yahoo Finance, citing Motley Fool, says about 119%. The small gap likely comes from the date or price used. Either way, Reuters ranks it the sixth-best bull market since World War Two and the eighth-longest, which it calls middle-aged.
Why AI gets the credit
Reuters says spending on AI is lifting corporate profits and economic growth, with S&P 500 earnings expected to rise more than 35% this year. Anthony Saglimbene of Ameriprise told Reuters the AI theme is the defining feature of this bull market, and that the easy money around AI has probably been made. For more on how AI news has moved chip stocks this week, see our OpenAI revenue story.
Does age matter?
Mark Hackett of Nationwide told Reuters that bull markets do not end of old age, they end from disease. Yahoo Finance, citing Motley Fool, says six earlier runs kept going after turning four, but four bear markets later took the index below its fourth-birthday level. Yahoo also notes the index trades near 26 times past-year earnings, above its 10-year average of 23.6.
Risks named
Reuters lists the Fed's rate hikes, rising Treasury yields, volatility ahead of next month's midterm elections and the market's dependence on AI. See our Waller story on rate hikes and oil.