Goldman Sachs' Scott Rubner said that US stock investors will have a brief "buying opportunity" window at the end of this month as selling pressure from systematic funds has eased and the company will increase share buybacks.

This Goldman Sachs global market director and tactical expert wrote in a report to clients on Monday, "This will be my last bearish view on the August stock market, as we are coming to the end of the period when the supply and demand mismatch in the stock market is most severe in August." He said he would switch to a tactical call on US stocks on August 30.

Rubner suggested at the end of June that investors reduce their exposure to the US stock market after July 4th, as he believed the stock market was in the "final stage of melt-up" before July 17th. Time also proved his point: the S&P 500 index fell about 6% after hitting a new closing high on July 16th.

After experiencing the crazy volatility last week, US stocks were almost unchanged on Monday, when investor concerns about the Fed waiting too long to cut interest rates caused huge market volatility. The S&P 500 index has fallen for the past four weeks in a row, the longest continuous decline since 2023. According to Goldman Sachs' data, rule-based systematic funds that follow market signals and volatility patterns have sold $109 billion worth of global equity derivatives in the past month.

Rubner believes that selling pressure will continue in the next seven days, but he said he "sees enough evidence and position reduction to indicate that the worst technical aspect of the market is behind us".

He said that the rebound in September "will be super clean and neat". He said he will buy on dips in the first half of this month and will remind everyone when everything becomes clear.

He wrote that another reason why the stock market may rebound is "the historically strong buyback window from August to September", second only to November to December. He added:

"We currently estimate that 90% of the stocks in the S&P 500 index will be in the buyback window, which will close again on September 6th. Companies may take advantage of this downturn and may buy $4.75 billion worth of stocks every day before the window closes."

However, Rubner warns investors that the outlook for US stocks will deteriorate after a certain point in September, as the second half of this month is the worst two weeks for the stock market this year. He wrote that there will not be a clear upward trend in the market for the remainder of the year until the fourth quarter and the US presidential election in November.

Editor/ping