We're about to find out how Americans really feel about the stock market

We're about to find out what Americans really think about the recent stock market chaos.

On Friday, the University of Michigan's preliminary reading on consumer confidence in September is expected to show consumers are a bit less confident than they were at the end of August.

Expectations are for the reading to come in at 91.1, down from 91.9 in August.

And while recent readings of consumer confidence have been high over the last year or so owing to a decline in gas prices, a rebound in home prices, and continued job gains, Ian Shepherdson at Pantheon Macro thinks Friday's report has real potential to disappoint due to the recent declines we've seen in the stock market.

"People don't like to see the value of their portfolios decline," Shepherdson wrote, "and it is just a matter of time before the benchmark measures of consumer sentiment drop in response to the 7% fall in the S&P since mid-August."

Shepherdson added: "Sometimes, movements in stock prices don't affect the sentiment numbers immediately, especially if the market moves gradually. But the drop in the market in August was rapid and dramatic, and gripped the national media. It would seem reasonable, therefore, to expect to see at least some reaction in the preliminary Michigan consumer sentiment data today."

In recent years, consumer confidence has declined in response to the debt ceiling crisis of 2011, the "Taper Tantrum" of 2013, and Shepherdson expects a similar drop will follow this time.

"We think the headline Michigan index will drop to about 85, well below the consensus," Shepherdson wrote, "but we would not be surprised by a significantly lower reading."

And while Shepherdson admits there are few reliable indicators of where Friday's reading could go, the TIPPOnline consumer confidence index - an online reading on consumer confidence - fell sharply this month and could portend a deep drop later today.