Comparando el mercado alcista del año 2025 con precedentes históricos

The scale of the 2025 rally is historic. The S&P 500 concluded the year with a 16.4% gain, marking the third consecutive year of double-digit returns. This pattern has occurred only five times in the index's history, a run that includes the dot-com boom and the post-pandemic recovery. The immediate question for 2026 is one of sustainability: can this streak continue, or does history warn of a reversal?

The path was volatile. The rally was built on a dramatic V-shaped recovery from a spring selloff triggered by aggressive tariff announcements. The market erased nearly $3 trillion in value in a single afternoon before bottoming and staging a powerful rebound. This recovery was fueled by a combination of corporate tax incentives, deregulation bets, and a critical liquidity backstop from the Federal Reserve, which cut rates three times in the final quarter.

The central thesis for the rally's strength is a "structural expansion" supported by the Fed's pivot. Yet, the engine was specific. The gains were driven by a wave of AI earnings growth, particularly in the physical infrastructure needed to power the digital revolution. This "Phase 2" AI cycle saw companies in memory and storage sectors post staggering returns, broadening the market's participation beyond tech giants.

Viewed through a historical lens, the setup is a classic tension. Past streaks of three straight 16%+ years have led to both explosive continuation and sharp corrections. The dot-com era saw surges followed by a crash, while the recent 2019-2021 run ended with a rate-hike induced bear market. The current record of consecutive gains is rare, but the valuation of the index now reflects high expectations, making the sustainability of the "structural expansion" thesis a critical test.

Structural Weaknesses: A Historical Lens

The 2025 rally's strength was built on a narrow foundation. Despite some broadening, market leadership remained heavily concentrated, with Artificial Intelligence remaining the resounding theme for the third consecutive year. The so-called Magnificent 7 have been responsible for about half of the S&P 500's gains over that period. While more sectors posted positive returns in 2025 than in prior years, the gains were still driven by a few dominant themes, creating a market that prices in perfection for a select group of companies.

This concentration has pushed valuations to historically high levels. The market's forward view now assumes continued flawless execution and growth, leaving little room for error. This setup is a classic vulnerability. History shows that after extended rallies, investors often begin to differentiate between winners and losers, leading to a rotation out of the most expensive, speculative names.

That rotation is already underway. In recent sessions, investors rotated out of high-growth technology stocks into other sectors, with semiconductor and AI-linked stocks leading the declines. This shift into defense and other cyclicals is a pattern seen after prior long bull markets. It signals early caution, as capital seeks perceived safety or value amid rising scrutiny over capital expenditures and growth assumptions. The move away from the AI infrastructure plays that powered the rally's final leg is a structural warning sign, suggesting the market's patience for pure growth narratives is thinning.

Forward Scenarios: What History Suggests

The immediate catalyst for 2026 is a familiar one: data and policy. Investors are watching the December jobs report for clues on labor market strength and the Federal Reserve's next move. At the same time, a potential Supreme Court ruling on the legality of recent tariffs looms, adding a layer of regulatory uncertainty. These factors will test the market's resilience as it enters a new year.

Historically, the setup here is a classic fork in the road. Following three consecutive years of double-digit gains, the S&P 500 has delivered wildly divergent results in the subsequent year. The record is mixed, with the index soaring again in some cases and falling sharply in others. After the dot-com boom streak from 1995 to 1997, the market jumped another 26.7% in 1998. Yet, the very next three-year run from 1997 to 1999 was followed by a decline of 10.1% in 2000, marking the start of a prolonged bear market. More recently, the 2019-2021 streak ended with a plunge of 19.4% in 2022 as the Fed raised rates to combat inflation. The path forward is not predetermined; history offers both a roadmap for continuation and a stark warning of reversal.

The primary risk to the bullish scenario is the translation of the AI narrative into hard earnings. The market's premium valuation now assumes a seamless "productivity miracle" that boosts corporate profits. If this materializes, the rally could extend. But if the expected efficiency gains fail to show up in financial statements, the premium would be challenged. This is the mirror of past "growth at any price" corrections, where the market's patience for pure narrative evaporates when fundamentals disappoint. The early rotation out of high-growth tech stocks is a sign that scrutiny is increasing.

The bottom line is one of high-stakes uncertainty. The market stands at a historical inflection point, with the potential for either a powerful extension of the rally or a sharp correction. The coming months will test whether the current "structural expansion" thesis is durable or if it is merely the final, euphoric leg of a historic cycle.