[1] Market prices are often subject to seasonal tendencies because the availability and demand for an item is not constant throughout the year.
For example, natural gas prices often rise in the winter because that commodity is in demand as a heating fuel.
[5] A 2018 study in the Eurozone concluded that calendar effects are not abnormal, citing the increase in market values around the end of the month, when employees are paid.
[7] A study published in 2001 argued that there is no statistically significant evidence for calendar effects in the stock market, and that all such patterns are the result of data dredging.
[8] However, there are contradictory findings and there is an ongoing debate on behavioral economics versus rational choice theory.