The S&P 500 has averaged a daily change of 0.01% so far in 2018. That's about as close to zero as it can get, but at least it's positive!

Below is a chart showing the S&P 500's average daily change by weekday so far in 2018. As shown, Monday, Wednesday, and Thursday have averaged declines, while Tuesday and Friday have averaged gains. Thursdays have been the worst day of the week, while Fridays have been the strongest.

In terms of volatility, the S&P has averaged an absolute change of +/-0.86% on all trading days so far in 2018. In 2017, which was one of the least volatile years in the history of the stock market, the S&P averaged an absolute daily change of just +/-0.30%.

Below we show how volatile each trading day of the week has been in 2018. As shown, the week has started and ended with a bang, while the middle days have been less volatile. On Mondays, the S&P has averaged a move of +/-1.15%. Tuesdays and Thursdays have averaged smaller moves of just over +/-0.80%, while Wednesdays have been the least volatile with an average change of +/-0.51%. Finally, Fridays have ended the week with an average absolute change of +/-1.03%.

The trend of volatile starts and ends to weeks and a calmer tone during the middle of the week has been in place for more than just 2018. Looking back over the last three years, a similar pattern has been in place. Mondays and Fridays have been the most volatile days of the week, and then things have gotten progressively less volatile from Tuesday through Thursday.