The longevity of the U.S. stock market rally may hinge on the outcome of the 2026 midterm elections, according to a team led by Bank of America Chief Investment Strategist Michael Hartnett.

In a recent report, Hartnett's team argued that the 2026 midterms represent a pivotal moment for the next phase of the market. If Republicans retain control of the Senate and Texas Governor Greg Abbott is re-elected, U.S. equities, particularly in the AI sector, could see further gains and potentially enter a "bubble-like" scenario extending into 2027. Conversely, if Democrats seize the Senate and defeat Abbott, the team predicts a correction of more than 10% in the stock market, accompanied by a decline in the dollar and bond yields.

This assessment comes as the market remains in a strong position, supported by earnings growth, wealth effects, and AI capital expenditure. However, fund flows and positioning are heavily skewed towards the upside, suggesting that any negative surprise in the election results could amplify market volatility.

The Texas Governor's Race: A Referendum on AI and the Cost of Living

Within the broader midterm landscape, Hartnett's team is particularly focused on the Texas gubernatorial election. Incumbent Republican Governor Greg Abbott faces a challenge from Democrat Gina Hinojosa. Bank of America characterizes this race as a "referendum on the cost of living versus AI data centers."

Texas currently hosts 335 data centers, with another 247 in the planning stages. Governor Abbott, a long-time supporter of business and data center expansion, recently announced a temporary pause on such growth. The team views this as a sign that rising energy costs and grid strain are translating into electoral concerns. A Republican-held Senate combined with Abbott's re-election would likely be interpreted as a green light for continued AI spending and data center expansion. In contrast, a Democratic sweep of both the Senate and the Texas governorship could trigger a significant repricing of AI investments and other risk assets.

Before the election results are known, the market must navigate a series of critical events, including Federal Reserve policy meetings, non-farm payrolls data, CPI reports, and the Bank of Japan's decision. Notably, the Fed's meeting on October 28 will occur just six days before the midterms, with the market currently pricing in approximately a 55% probability of a rate hike.

Trillion-Dollar AI Spending Fuels the Rally, but Extreme Positioning Creates Fragility

Hartnett's team believes the current environment is one of high risk appetite, with AI remaining a core offensive driver. Robust corporate earnings growth, a projected $10 trillion wealth effect by 2026, and estimated AI capital expenditure exceeding $1 trillion by 2027 collectively provide ammunition for risk assets to move higher.

In terms of fund flows, the week ending August 12 saw $161 billion flow into equities, $238 billion into bonds, and $63 billion into gold. U.S. equities attracted $15.6 billion, marking the third consecutive week of inflows.

However, this optimism is already reflected in crowded positioning. Bank of America's "Bull & Bear Indicator" currently stands at 9.3, remaining in a "sell" signal zone. Fund manager equity allocations are at the 99th percentile, while equity fund flows are at the 90th percentile. The team notes that while extreme positioning does not necessarily signal an immediate end to the bull market, it makes the market highly sensitive to unexpected negative news.

Earnings and AI Capex Still Support the Bull Case

From a fundamental perspective, the current bull market retains strong support. Second-quarter earnings for S&P 500 companies grew 32%, significantly exceeding the 23% forecast at the start of the reporting season. Bank of America argues that this strong earnings momentum, combined with the ongoing expansion of AI capital expenditure, will continue to provide upward momentum for risk assets.

As of August 12, U.S. stocks are up roughly 14% for the year, while markets heavily tied to the AI supply chain, such as South Korea's KOSPI index, have surged 78.7%.

Hartnett cautions against simply labeling the current environment as the late cycle of a bull market. A true market top typically requires the simultaneous presence of excessive positioning, overly optimistic earnings expectations, and tightening monetary policy. While the market is crowded, earnings growth and the AI investment cycle are still providing support.

Bond Yields Pose the Greatest Constraint

The bond market represents the most significant potential risk for this rally. Total U.S. government debt is approaching $40 trillion and could reach $50 trillion by 2029. Over the past 12 months, the U.S. government has spent approximately $1.4 trillion on interest payments, a figure that is under pressure to rise further in a high-rate environment.

Bank of America suggests that government debt servicing costs will only ease significantly when the 5-year Treasury yield falls below 3.25%. Meanwhile, the 30-year Treasury yield recently touched 5.126%, a 25-year high. However, some long-duration assets that were previously out of favor, such as REITs, biotech, banks, and small-cap stocks, have recently started to outperform. This could indicate that the market is beginning to price in a "peak in yields" rather than a continued upward trend. The team warns that a rapid further rise in yields would become increasingly difficult for policymakers to tolerate.

The Biggest Risk: Overcrowded Longs

In Hartnett's view, the most significant threat to the current rally stems from the market's own optimism. Bank of America's private client equity allocation has risen to a record 66.4%, while bond allocation has fallen to 17% (its lowest since March 2022) and cash allocation has dropped to a record low of 9.4%. Furthermore, private client equity fund inflows were the largest in a single week since September 2022.

This suggests that if positive catalysts continue to materialize, the market has room to move higher. However, should there be any disappointment from elections, interest rates, or AI earnings expectations, the crowded long positioning could amplify a market downturn. Hartnett's team outlines three key constraints for the current market: surging bond yields, changing voter sentiment, and the fact that "everyone is already betting on the upside." For this AI-driven rally, the midterm elections may well be the critical test of whether the bull market transitions from "strong gains" to a "bubble frenzy."