Calendar Effects

Does the Memorial Day holiday signal any unusual U.S. stock market return effects? By its definition, this holiday brings with it any effects from three-day weekends and sometimes the turn of the month. Prior to 1971, the U.S. celebrated Memorial Day on May 30. Effective in 1971, Memorial Day became the last Monday in May. To investigate the possibility of short-term effects on stock market returns around Memorial Day, we analyze the historical behavior of the stock market during the three trading days before and the three trading days after the holiday. Using daily closing levels of the S&P 500 Index for 1950 through 2025 (74 observations), we find that: Keep Reading

Does the conventional wisdom to “Sell in May” (and “Buy in November”, hence also the term “Halloween Effect”) work over the long run, perhaps due to biological/psychological effects of seasons (Seasonal Affective Disorder)? To check, we turn to the long run dataset of Robert Shiller. This data set includes monthly levels of the S&P Composite Index, calculated as average of daily closes during the month. We split the investing year into two half-years (seasons): May through October, and November through April. Using S&P Composite Index levels, associated dividend yields and contemporaneous long-term interest rates (comparable to yields on 10-year U.S. Treasury notes) from the Shiller dataset spanning April 1871 through April 2026, we find that: Keep Reading

We have updated monthly allocations and performance data for the Simple Asset Class ETF Momentum Strategy (SACEMS) and the Simple Asset Class ETF Value Strategy (SACEVS). We have also updated performance data for the Combined Value-Momentum Strategy.

We have updated the Trading Calendar to incorporate data for April 2026.

Does the seasonal shift marked by the Easter holiday, with the U.S. stock market closed on the preceding Good Friday, produce anomalous returns? To investigate, we analyze the historical behavior of the S&P 500 Index before and after the holiday. Using daily closing levels of the S&P 500 index for 1950-2025 (76 events), we find that: Keep Reading

The Trading Calendar has links to charts of average month-to-date return for the S&P 500 Index (SP500) by trading day during each month of the year. How do these cumulative return profiles compare? To illustrate, we construct a single chart that shows average cumulative return profiles within all 12 months. Using daily SP500 levels during January 1990 through February 2026 (a “modern” era), we find that: Keep Reading

“Seasonal Strategy for QQQ?” finds an interesting even year-odd year effect in Invesco QQQ Trust (QQQ) annual returns. The Trading Calendar and “Monthly Returns During Presidential and Congressional Election Years” find notable differences in S&P 500 Index performances for even years and odd years. A plausible culprit is federal elections. Is this effect growing over time? To investigate, we look at four indexes over their full histories:

1. Shiller’s S&P Composite Index during 1871 through 2025 (154 annual returns).
2. The S&P 500 Index during 1927 through 2025 (98 returns).
3. The NASDAQ 100 Index during 1985 through 2025 (40 returns).
4. The Russell 200 Index during 1987 through 2025 (38 returns).

For each index, we calculate annual returns for even years and odd years and look at the separate trends in these returns over time. Using the selected end-of-year index levels, we find that: Keep Reading

Are some years of the decade better than others for equity markets? To investigate, we look at average annual returns by year of the decade (xxx0 through xxx9) for the U.S. stock market. Using annual levels of Shiller’s S&P Composite Index for 1871-2025 and the S&P 500 Index for 1928-2025, we find that: Keep Reading

Investor mood may affect financial markets. Sports may affect investor mood. The biggest mood-mover among sporting events in the U.S. is likely the National Football League’s Super Bowl. Is the week before the Super Bowl especially distracting and anxiety-producing? Is the week after the Super Bowl focusing and anxiety-relieving? Presumably, post-game elation and depression cancel between respective fan bases. Using past Super Bowl dates since inception and daily/weekly S&P 500 Index levels for 1967 through 2025 (59 events), we find that: Keep Reading

The full-year Trading Calendar indicates that the U.S. stock market has three phases over the calendar year, corresponding to calendar year trading days 1-84 (January-April), 85-210 (May-October) and 211-252 (November-December). What are typical stock market returns and return variabilities for these phases? Using daily S&P 500 Index closes from the end of December 1927 through December 2025, we find that: Keep Reading

Does the New Year’s Day holiday, a time of replanning and income tax positioning, systematically affect investors in a way that translates into U.S. stock market returns? To investigate, we analyze the historical behavior of the S&P 500 Index during the five trading days before and the five trading days after the holiday. Using daily closing levels of the S&P 500 Index around New Year’s Day for 1951-2025 (75 observations), we find that: Keep Reading