Markets remain in this negative period leading into the US tax deadline day of April 18. Ten of the past twenty weeks leading into the deadline date have produced a loss averaging 2.24% for the S&P 500 index. Conversely 15 of the past 20 weeks following the deadline have produced gains averaging 1.65%. The day of the deadline itself also tends to be particularly positive with an average positive return of 0.34%. Almost three-quarters of the tax deadline dates tend to be positive for the S&P 500 index.