Happy birthday to the bull market, which just turned four.

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.

Technically speaking, the path forward appears less ideal.

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.

Small caps, especially, have suffered. Oppenheimer’s Wald said he’s closely watching the Russell 2000’s test of its 200-day moving average to see whether the bull market still has room to run.

“In our view, relative weakness remains a warning, not an opportunity, until stronger market conditions can be reestablished,” Wald wrote.

Earnings are also an issue. While the third-quarter reporting season is expected to be strong, some worry that they may not be strong enough to lift the stock price given how high expectations have grown.

Tech, in particular, is an issue. Deutsche Bank strategist Parag Thatte wrote that he thinks the rotation into tech is now overdone, with the risk-reward no longer looking favorable.

But many investors remain optimistic in the stock market, as its resilience over the last four years reflects strong fundamental earnings amid the AI build-out — though picking the winners may get trickier.

“In order to outperform, investors need a combination of owning stocks that grow fast and don’t miss — which remains our mantra,” Adam Parker, founder of Trivariate Research, wrote on Sunday.

He later added: “We continue to think that the US stock market will perform well.”