That estimate isn't surprising given the rebound that we've seen in several recent economic data reports, including retail sales, durable goods orders and ISM manufacturing data have all been strong.
October kicks off a period of seasonal strength, it has been a strong month for the stock market for more than 30 years and the 4th quarter of the year is historically the best quarter of the year. Markets are usually bolstered in the last three months of the year, (including election years) as we enter into the holiday season and consumers spend more on Halloween, Thanksgiving and the Christmas holiday which boosts economic activity.
The chart below from Bespoke shows the average historical investment performance of the S&P 500 for prior years for the upcoming week, month and 3 months period.