(Bloomberg) -- Tariffs imposed on China during President-elect Donald Trump’s first term had negative effects for the US economy, according to newly released research from the Federal Reserve Bank of New York.

The findings come as Trump has threatened to wield tariffs more aggressively against US trading partners when he takes office in January, injecting new uncertainties into the US economic outlook.

The New York Fed researchers found tariffs announced in 2018 and 2019 of 10% to 50% on more than $300 billion of imports from China led to “a negative effect on the US economy that is substantially larger than past estimates.”

They found the US stock market fell 11.5% on days when the tariffs were announced, amounting to a $4.1 trillion loss in firm equity value. The declines were persistent and markets didn’t bounce back in the week following the announcements, according to the researchers.

The announcements also spurred a “flight to safety” among investors, sending Treasury yields lower and equity premia — the rate of return on stocks relative to safer assets — higher, the researchers said.

Taking these market reactions together and considering their impact on dividend income, interest income, labor income and tax revenues, the researchers found the tariff announcements lowered expected welfare by 3%.

“It is significantly larger than the welfare predictions from standard trade models,” the researchers wrote. “This finding suggests that these models may overlook important channels by which tariffs could affect the economy, such as the dampening effect of tariffs on innovation, the negative consequences of increased trade uncertainty on investment or the destabilizing impact of tariff announcements on global trade policies.”