Weakness in stock markets is spreading across major indexes, but the selling could end soon, Kristina Hooper, U.S. investment strategist at Allianz Global Investors, said Thursday.

Dow futures plunged 300 points on Thursday, following European markets, which fell on renewed concerns about the continent's banks .

Some investors also seemed to be worried by remarks from Janet Yellen during her testimony before Congress on Wednesday.

The Federal Reserve chair suggested global weakness and risks in China could dent the U.S. economy, and said the Fed was not yet certain whether it could legally induce negative interest rates, a path Japan's central bank has embarked upon.

But Hooper said she did not think Yellen's comments were behind the fresh leg downward for stocks.

"It seems more like contagion. What started off as, really, a healthy correction has turned into an oversold situation with some elements of panic," she told CNBC's "Squawk Box."

To be sure, contagion is not spreading to the real economy, but within markets themselves, she said. Hooper said the return of Asian traders following the Lunar New Year holiday was bound to exacerbate the sell-off.

In Allianz's view, the United States is likely to skirt a recession, so equity valuations no longer look stretched and stocks are now starting to look more attractive.

The market needs big buyers to start capitalizing on the price slide in order to turn around, she said. That could happen relatively soon, but probably not in the next few days, she added.

Corporate executives are working to minimize the damage by buying up shares of their own company, JP Morgan Private Bank strategist Jack Caffrey said Thursday.

Shares of Amazon.com (NASDAQ: AMZN) bounced Wednesday after the company said it would buy back $5 billion worth of its stock .

Goldman Sachs Chief U.S. Equity Strategist David Kostin on Tuesday said the absence of corporate buybacks ahead of earnings season was largely to blame for a dismal January for U.S. stocks.

As for Yellen's comments on Wednesday, Caffrey noted that the Fed has no mandate to worry about the stock market. The central bank is in a tough spot because as stocks slide, the United States is making progress in the arenas where the Fed does have a mandate: promoting full employment and price stability.

"Clearly there's a psychological element, which is at some point you can't have chaos," he told "Squawk Box." "But to some extent if you also spend all of your time changing your commentary, changing your forecast like a pinball machine, that leads to less confidence, rather than more."

Caffrey said he worries less about contagion from China and more about the threat of banks tightening lending across industries as they react to the threat of loan losses in the beaten-up energy sector. He noted that a survey of senior loan officers last week indicated banks are becoming more conservative when it comes to lending.

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