Core Insights - The S&P 500 Index (SPX) has historically struggled during the week of Martin Luther King Jr. Day, averaging a loss of 0.49% with only 43% of weeks ending positively [3][5]. Historical Performance - The SPX has an average return of -0.49% during Martin Luther King Jr. week compared to an average return of 0.18% during other weeks, with 57% of other weeks ending positively [3][4]. - The median return for Martin Luther King Jr. week is -0.18%, while it is 0.28% for other weeks [5]. Daily Breakdown - Tuesday typically starts poorly with an average loss of 0.22%, and historically, the SPX has been down the day after Martin Luther King Jr. Day in seven of the past nine years [7]. - Wednesday is usually the only day with an average positive return of 0.16%, while Friday tends to be the worst day with an average loss of 0.30% [8]. Top Performing Stocks - Nvidia (NVDA) has the highest average return of 2.25% during Martin Luther King Jr. week, with a 90% positive return rate [11][12]. - Workday (WDAY) has outperformed the SPX every year over the past ten years, also achieving a 90% positive return rate [11][12]. Underperforming Stocks - CF Industries (CF) has the worst average return at -4.46%, with only a 10% positive return rate [14][15]. - Other notable underperformers include Northern Trust (NTRS) and Halliburton (HAL), both with average returns below -2.75% [14][15].