The technical problem with buying stocks now

Stocks have managed to bounce nicely over the last two weeks, after a swift drop in late August. But the worst may not be over for stocks, says Oppenheimer technical analyst Ari Wald, whose examination of market seasonality suggests a cautious outlook.

"Seasonal trends remain very bearish for the next month," Wald said in a Tuesday "Trading Nation" segment. "September as a whole is one of the worst-performing months of the year for the stock market going back to 1950, and when you look into those numbers, September is even worse when the S&P ends August below its 200-day moving average," referring to an indicator that records the average of the prior 200 closing prices.

"When it's in a downtrend, when you have weakness going into September, markets tend to get even weaker," Wald said.

The technician suggests that the S&P 500, which opened Wednesday at 1,971, has resistance just overhead at 2,000, and could fall below 1,900 within the month.

However, trader Boris Schlossberg of BK Asset Management has a different take on the numbers.

"If you look seasonally past September, it's actually been a very good time to buy into October and November, when the market tends to rally over the last 10 years. So now might be a time to start accumulating into that potential rally," Schlossberg said Tuesday.

Read MoreStocks close down 1.4% despite global rally


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Trading Nation is a multimedia financial news program that shows investors and traders how to use the news of the day to their advantage. This is where experts from across the financial world – including macro strategists, technical analysts, stock-pickers, and traders who specialize in options, currencies, and fixed income – come together to find the best ways to capitalize on recent developments in the market. Trading Nation: Where headlines become opportunities.

Michael Santoli

Michael Santoli joined CNBC in October 2015 as a Senior Markets Commentator, based at the network's Global Headquarters in Englewood Cliffs, N.J.  Santoli brings his extensive markets expertise to CNBC's Business Day programming, with a regular appearance on CNBC's “Closing Bell (M-F, 3PM-5PM ET).   In addition, he contributes to CNBCand CNBC PRO, writing regular articles and creating original digital videos.

Previously, Santoli was a Senior Columnist at Yahoo Finance, where he wrote analysis and commentary on the stock market, corporate news and the economy. He also appeared on Yahoo Finance video programs, where he offered insights on the most important business stories of the day, and was a regular contributor to CNBC and other networks.

Follow Michael Santoli on Twitter @michaelsantoli

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