Despite an upbeat market forecast for the year's second half, Ally Invest's Lindsey Bell has a warning for the next few months.
Bell finds the third quarter is usually the weakest time of the year, up 0.7% on average since 1950.
However, she suggests it's no reason to get discouraged.
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"The fourth quarter is where you usually see the pickup," the firm's chief investment strategist told CNBC's "Trading Nation" on Wednesday.
Her forecast comes with the S&P 500 ending 2021's first half at all-time highs. So far this year, it's up more than 14%. Plus, the index is on a five-month win streak.
Money Report
What could spook the market near term? Bell says headline risks associated with Federal Reserve policy.
"Investors have been skittish. They have gotten a little bit nervous about this topic in general," said Bell, a CNBC contributor. "What we have seen is that the Fed raising rates has contributed to a peak in the stock market over different periods of time."
Yet, Bell calls herself "cautiously optimistic" and expects Wall Street to effectively work through potential jitters.
"The peak in the stock market doesn't typically happen when the Fed begins its rate-tightening process," she said. "You shouldn't be too worried about the Fed tightening anytime soon. But they will be coming probably next year or the year after."
For the next six months, Bell prefers to continue using a barbell approach to investing. She wants equal weights of growth, including Big Tech, and economically sensitive stocks.
Bell predicts earnings per share and GDP growth projections will continue to grow in the second half and support the market. She also sees a world where tech stocks get a strong bid due to a slowing in the economic recovery.
"It could be an area where investors start to turn to put their money simply because growth is expected to peak in the second quarter," Bell said.