The Rotterdam School of Management has been mentioned in an article. The article states that stock markets and stock returns are better in the winter and experience declines in summer. The Rotterdam School of Management states: "Surprisingly we found this inherited wisdom of Sell in May to be true in 36 of 37 developed and emerging markets. Evidence shows that in the United Kingdom the seasonal effect has been noticeable since 1694.... A trading strategy based on this anomaly would be highly profitable in many countries. The average annual risk-adjusted outperformance ranges between 1.5% and 8.9%, depending on the country being considered. The effect is robust over time, economically significant, unlikely to be caused by data-mining, and not related to taking excess risk."