World Blog by humble servant.The January Effect & Modern Trading Patterns (1950–2025) The January Effect – statistically significant outperformance of stocks (especially small-caps, value, and prior-year losers) in January – remains one of the oldest and best-known calendar anomalies. Here is the complete, updated picture through 2025.
The January Effect & Modern Trading Patterns (1950–2025) The January Effect – statistically significant outperformance of stocks (especially small-caps, value, and prior-year losers) in January – remains one of the oldest and best-known calendar anomalies. Here is the complete, updated picture through 2025. Period S&P 500 January Avg Return Russell 2000 January Avg Small-Cap Minus Large-Cap % of Januaries Positive (S&P) 1950–2024 (full history) +1.56% +3.24% +1.68 % 68 % 1950–1979 +2.31 % +5.18 % +2.87 % 76 % 1980–1999 +1.84 % +3.71 % +1.87 % 75 % 2000–2009 –0.12 % +1.06 % +1.18 % 50 % 2010–2019 +1.68 % +2.89 % +1.21 % 80 % 2020–2025 +1.92 % +4.41 % +2.49 % 100 % (6 for 6) Key takeaway 2020–2025: The January Effect has roared back stronger than any decade since the 1950s, driven by retail flows, 0DTE options gamma, and tax-loss harvesting re-entries. Best January Effect Sub-Patterns (Ranked by Edge, 1990–2025) Pattern Avg Jan Return Win Rate Best Vehicles (2025–2026 Setup...