Calendar Effects

Does the Christmas holiday, a time of putative good will toward all, give U.S. stock investors a sense of optimism that translates into stock returns? To investigate, we analyze the historical behavior of the S&P 500 Index during five trading days before through five trading days after the holiday. Using daily closing levels of the S&P 500 Index for 1950-2024 (75 events), we find that: Keep Reading

How material is the rebalance timing luck (RTL) induced by picking a trading day to reform a monthly stock momentum strategy? Is there a way to manage the risk of bad luck? In their November 2025 paper entitled “The Tranching Dilemma. A Cost-Aware Approach to Mitigate Rebalance Timing Luck in Factor Portfolios”, Carlo Zarattini and Alberto Pagani investigate monthly momentum portfolio tranching, holding multiple portfolios with the same strategy but with different reformation cycles, as a way to manage RTL. Their test strategy each month:

1. Identifies the 1,000 most liquid components of the Russell 3000 Index.
2. Finds the 100 stocks with highest total returns from 12 months ago to one month ago.
3. Reforms an equal-weighted portfolio of the 20 out of these 100 stocks with the highest momentum quality based on the percentage of days with positive and negative returns during the ranking interval.

They run this strategy with reformation cycles from the close on trading day one of each month to the close on trading day 20 (or last) of each month. They then consider effects on RTL of holding 2, 4, 5, 10 and 20 tranches across these cycles. They assume portfolio reformation frictions as standard Interactive Brokers fee of $0.0035 per share with minimum $0.35 per trade (doubled for sell transactions to account for SEC clearing fees). Using daily data for Russell 3000 Index components during 1991 through 2024, they find that:

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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 November 2025.

Does the Thanksgiving holiday, a time of families celebrating plenty, give U.S. stock investors a sense of optimism that translates into stock returns? To investigate, we analyze the historical behavior of the S&P 500 Index 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 1950-2024 (75 events), we find that: Keep Reading

Are some calendar months more likely to exhibit stock market continuation or reversal than others, perhaps due to seasonal or fund rebalancing/reporting effects? In other words, is intrinsic (times series or absolute) momentum an artifact of some months or all months? To investigate, we relate U.S. stock index returns for each calendar month to those for the preceding 3, 6 and 12 months. Using monthly closes of the S&P 500 Index since December 1927 and the Russell 2000 Index since September 1987, both through September 2025, we find that: Keep Reading

Is there a reliable and material market capitalization (size) effect among U.S. stocks around the turn-of-the-year (TOTY)? To check, we track cumulative returns from 20 trading days before through 20 trading days after the end of the calendar year for the Russell 2000 Index, the S&P 500 Index and the Dow Jones Industrial Average (DJIA) since the inception of the Russell 2000 Index. We also look at full-month December and January returns for these indexes. Using daily and monthly levels of all three indexes during December 1987 through January 2025 (38 December and 38 January observations), we find that: Keep Reading

Do gold and gold mining stocks exhibit exploitable seasonality? Using monthly closes for spot gold and the S&P 500 Index since December 1974, PHLX Gold/Silver Sector (XAU) since December 1983, AMEX Gold Bugs Index (HUI) since June 1996 and SPDR Gold Shares (GLD) since November 2004, all through September 2025, we find that: Keep Reading

Does the Turn-of-the-Month Effect, a concentration of positive stock market returns around the turns of calendar months, work across a broad set of asset classes. To investigate, we measure turn-of-the-month (TOTM) returns for the following nine asset class exchange-traded funds (ETF) used in the “Simple Asset Class ETF Momentum Strategy” and the “Simple Asset Class ETF Value Strategy”:

• Invesco DB Commodity Index Tracking Fund (DBC)
• iShares MSCI Emerging Markets Index (EEM)
• iShares JPMorgan Emerging Markets Bond Fund (EMB) 
• iShares MSCI EAFE Index (EFA)
• SPDR Gold Shares (GLD)
• iShares Russell 2000 Index (IWM)
• iShares iBoxx $ Investment Grade Corporate Bond (LQD)
• SPDR S&P 500 ETF Trust (SPY)
• iShares Barclays 20+ Year Treasury Bond (TLT)
• Vanguard REIT ETF (VNQ)

We define TOTM as the eight-trading day interval from the close five trading days before the first trading day of a month to the close on the fourth trading day of the month. Using daily dividend-adjusted closes for these ETFs from their respective inceptions (ranging from February 1993 for SPY to December 2007 for EMB) through late September 2025, we find that: Keep Reading

A reader inquired whether the Turn-of-the-Month Effect, a concentration of positive stock market returns around the turns of calendar months, works for U.S. stock market sectors. To investigate, we measure turn-of-the-month (TOTM) returns for the nine sector exchange-traded funds (ETF) defined by the Select Sector Standard & Poor’s Depository Receipts (SPDR), all of which have traded since December 1998:

• Materials Select Sector SPDR (XLB)
• Energy Select Sector SPDR (XLE)
• Financial Select Sector SPDR (XLF)
• Industrial Select Sector SPDR (XLI)
• Technology Select Sector SPDR (XLK)
• Consumer Staples Select Sector SPDR (XLP)
• Utilities Select Sector SPDR (XLU)
• Health Care Select Sector SPDR (XLV)
• Consumer Discretionary Select SPDR (XLY)

We define TOTM as the eight-trading day interval from the close five trading days before the first trading day of a month to the close on the fourth trading day of the month. Using daily dividend-adjusted closes for the sector ETFs and for SPDR S&P 500 ETF Trust (SPY) as a benchmark from December 1998 through late September 2025, we find that: Keep Reading

Some stock market experts cite the year (1, 2, 3 or 4) of the U.S. presidential term cycle as a useful indicator of U.S. stock market returns. Game theory suggests that presidents deliver bad news immediately after being elected and do everything in their power to create good news just before ensuing biennial elections. Are some presidential term cycle years reliably good or bad? If so, do abnormal returns concentrate in certain quarters? Finally, what does the stock market do in the period immediately before and after a national election? Using daily and monthly S&P 500 Index levels from January 1928 through July 2025 (about 97 years and 24 presidential terms) and focusing on “political quarters” (Feb-Apr, May-Jul, Aug-Oct and Nov-Jan), we find that: Keep Reading