Goldman Sachs Group (GS), Carlyle Group (CG) and Jefferies Financial Group (JEF) were downgraded by Oppenheimer to perform from outperform amid the "likely" delayed or cancelled rebound in M&A activity this year.

"We fear that the current uncertainty over tariffs, a fiscal 'detox' and the general upheaval of 80 years of trade and security arrangements is likely to cause a pause in M&A activity," Oppenheimer said in a note Wednesday.

The firm said that coming into the year, it was "very optimistic about a major rebound" in M&A and its attendant financing due to pent-up demand, stable to lower interest rates, tight credit spreads and "generally strong" public market stock valuations.

But Oppenheimer said there has been "no visible sign of this M&A rebound" so far.

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