The bull market turned 4 years old on Monday. Investors say reaching a fifth birthday could be challenging

Monday marks the fourth anniversary of the current bull market, with the S&P 500 having climbed nearly 120% since its closing low on Oct. 12, 2022 — an extraordinary run that reflects Wall Street's faith in the transformative power of artificial intelligence.

Since the release of ChatGPT in late 2022 , investors have hungered for all things related to the AI trade, with the stocks most tied to the build-out — the so-called "picks and shovels" — flying to whole new stratospheres because of the technology.

Nvidia , the poster child for the revolution that was formerly best known for the graphics cards it built for high-end video games, is now a roughly $5.5 trillion company; it passed the $1 trillion market cap for the first time in 2023. Micron Technology , another beneficiary, passed the $1 trillion market cap for the first time this May .

Those moves have helped the stock market climb a wall of worry in the intervening years, including in 2026. The S&P 500 just last week topped 7,800 for the first time, and remains near records, thanks in large part to its heavy allocation toward tech. About 40% of the broader index is in tech stocks.

After such an extraordinary run, investors wonder how much longer the rally can continue, especially as they face ongoing fears around higher inflation, surging bond yields and a more hawkish Federal Reserve .

According to Oppenheimer's Ari Wald, the current bull market is the sixth longest of 24 going back to 1932. In observing the data, the chart analyst wrote that the median time remaining before a cycle reached its peak was 13 months, which suggests 2027 could be the final leg of the run.

To be sure, Wald added that the median fifth year return was still 21%, suggesting there are further gains to be had for investors before any peak.

How much longer the current cycle can continue may depend on market breadth, which has deteriorated. In September, 75% of stocks in the S&P 500 closed in negative territory , as the threat of higher interest rates spurred investors back into a few mega-cap companies.