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

The bull market recently celebrated its four-year anniversary.

As of Monday, the current bull market has officially reached its fourth year, with the S&P 500 experiencing an impressive increase of nearly 120% since its closing low on October 12, 2022. This remarkable growth is primarily attributed to Wall Street's confidence in the revolutionary potential of artificial intelligence.

Following the launch of ChatGPT in late 2022, there has been a significant investor interest in AI-related stocks. Companies associated with the infrastructure and support for this technological advancement—often referred to as the "picks and shovels"—have seen their valuations soar.

Nvidia, a leading player in this space, which gained prominence for its graphics cards serving high-end video gaming, has now reached a market capitalization of approximately $5.5 trillion, having surpassed the $1 trillion threshold for the first time in 2023. Similarly, Micron Technology achieved a $1 trillion market cap for the first time in May 2026.

These developments have provided momentum for the stock market, enabling it to navigate various challenges over the years, including in 2026. Recently, the S&P 500 reached a new peak of 7,800, remaining close to all-time highs, largely due to its significant allocation to technology stocks, which make up around 40% of the index.

However, following such an extraordinary performance, investors are questioning the longevity of this rally, particularly in light of ongoing concerns regarding rising inflation, escalating bond yields, and a more assertive Federal Reserve.

From a technical perspective, the outlook appears somewhat less favorable.

Ari Wald from Oppenheimer notes that the current bull market ranks as the sixth longest since 1932 out of 24 recorded bull markets. He observed that, based on historical data, the median time remaining before a market cycle peaks is approximately 13 months, suggesting that 2027 could potentially mark the end of the current uptrend.

Wald also pointed out that the median return during the fifth year of a bull market typically stands at 21%, indicating that opportunities for growth still exist for investors before reaching a peak.

The continued viability of this cycle may hinge on market breadth, which has shown signs of weakening. In September, a significant 75% of S&P 500 stocks closed lower, as higher interest rates prompted a reallocation of investments towards select mega-cap companies.

Small-cap stocks, in particular, have faced challenges. Wald emphasized that he is monitoring the Russell 2000's performance relative to its 200-day moving average to assess the bull market's potential for further advancement.

"In our view, relative weakness remains a warning rather than an opportunity until more robust market conditions are established," Wald stated.

Earnings reports are also a critical factor. Although the upcoming third-quarter earnings season is anticipated to be strong, some analysts express concerns that these results may fall short of the elevated expectations that have developed.

In the technology sector, the situation is of particular concern. Parag Thatte, a strategist at Deutsche Bank, voiced his belief that the recent rotation into tech stocks may have become excessive, with the current risk-reward profile appearing less attractive.

Nonetheless, a number of investors continue to express optimism regarding the stock market, as its resilience over the past four years is indicative of solid fundamental earnings amidst the advancements in AI—though identifying the most promising investments may prove to be increasingly complex.

"To achieve superior performance, investors must focus on a mix of stocks that exhibit rapid growth and consistently meet expectations, which remains a key principle for us," stated Adam Parker, founder of Trivariate Research. "We still anticipate strong performance from the US stock market."