S&P 500's Rare Triple-Digit Streak: Breaking Down 97 Years of History to Decode 2026's Path

The Numbers Tell a Story

The S&P 500 wrapped up 2025 with a 16.4% gain, marking the third consecutive year of double-digit-plus returns. This milestone doesn’t happen often. In the 97-year history of modern stock indexing (since the S&P 90 launched in 1928), the index has managed to post three straight years of 16%+ returns only five times.

The current streak—with 24.2% (2023), 23.3% (2024), and 16.4% (2025)—joins a select club. The first and most famous occurred during the dot-com era: 1995-1997, followed by overlapping runs in 1996-1998 and 1997-1999. Two decades of market volatility passed before the next triple-digit stretch materialized: 28.9% (2019), 16.3% (2020), and 26.9% (2021).

History’s Divided Verdict

When examining what happens after such streaks, the historical record splits sharply into two camps.

The Bull Case: Following the 1995-1997 run, the S&P 500 accelerated with a 26.7% surge in 1998. The 1996-1998 streak led to a 19.5% jump in 1999. This pattern suggests momentum can persist, especially when structural drivers remain intact.

The Bear Case: The dot-com bubble burst after the 1997-1999 triumvirate, sending the index down 10.1% in 2000—the beginning of a multi-year bear market. More recently, the 2019-2021 streak gave way to a 19.4% crash in 2022 when the Federal Reserve aggressively hiked rates to combat inflation.

So where does 2026 stand?

The AI Question vs. The Valuation Trap

Two competing narratives are emerging.

Tailwind: The 1990s rally was fueled by e-commerce adoption and the internet’s transformative power. Today’s analog is artificial intelligence. If companies translate AI investments into measurable returns during 2026, expect continued rallies similar to the late 1990s momentum.

Headwind: The S&P 500’s Shiller CAPE ratio—a premier valuation metric—sits at its highest level since the 2000 dot-com peak. That year, elevated valuations combined with disappointing earnings expectations triggered a sharp correction. Valuations alone don’t cause crashes, but they set the stage. If 2026 disappoints on AI monetization or macro headwinds return, this lofty valuation becomes a vulnerability.

The Uncertainty Premium

Unlike the 1990s or the 2019-2021 rebound, 2026 lacks a clear playbook. The index could either mirror late-1990s exuberance or replicate 2000’s reckoning—or something in between.

Why Long-Term Investors Can Sleep

Amid the noise, one historical streak truly matters: over every rolling 20-year period in S&P 500 history, positive total returns occurred 100% of the time. This pattern has held regardless of valuations, recessions, or boom-bust cycles.

For those not trying to time 2026, this speaks louder than any annual forecast.