New York (CNN Business) JPMorgan Chase CEO Jamie Dimon said corporate tax cuts boosted the bank's profits to the tune of $3.7 billion last year.

In his annual letter to shareholders, Dimon noted that the Trump administration's tax reform was a key factor in the bank's record $32.5 billion haul. US bank profits, which were also buoyed by a healthy economy, reached all-time highs in 2018.

"For the long term, we expect that some or eventually most of that increase will be erased as companies compete for customers on products, capabilities and prices," Dimon said. "However, we did take this opportunity in the short term to massively increase our investments."

The yearly letter is a must-read on Wall Street, where Dimon, who also heads the powerful Business Roundtable, is the longest serving chief executive. He's known to weigh in not just on the bank's performance, but also on the broader economic environment and public policy.

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This year, Dimon offered a defense of capitalism, which he called "the most successful economic system the world has ever seen."

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