Oct. 12 would mark four full years for the current bull market, making it the seventh since the 1950s to reach that milestone, according to Truist.
A 119% advance puts this run near the middle of the historical pack, but Truist said continued economic growth, resilient profits and lower valuations still support stocks even as volatility risks rise.
FactSet expects S&P 500 third-quarter earnings growth of 29.5%, which would be the third straight quarter above 25% and the eighth consecutive quarter of double-digit gains.
AI demand is reinforcing that backdrop: Barclays said semiconductor and hardware companies account for about 40% of 2026 S&P 500 estimate revisions and 75% of 2027 revisions.