Citadel Securities' Scott Rubner is growing increasingly constructive on what comes next as US equities head into the final quarter of the year. Investors can expect a bumpy ride in the immediate future, but increasing weakness through the end of the month should be used to pile back into core parts of the market, he said. Artificial intelligence sentiment has turned sharply negative and positioning has been reduced -- trends that should start to work in the other direction starting in October, first in tech, and then across the broader market.

The outlook suggests a potential turning point for market sentiment in the coming months.