Chinese retaliation against President Donald Trump's tariffs is hitting U.S. exporters harder than their Chinese counterparts and costing the U.S. the equivalent of about $40 billion a year in lost exports, according to a new study that highlights the mounting costs to the U.S. economy of the trade war against China.

U.S. tariffs imposed last year on some $250 billion in imports from China slowed shipments of the targeted products to U.S. shores, according to findings from the Institute of International Finance (IIF) published earlier this year. Now, a new IIF study of China's retaliation has found that counter-tariffs had a far more severe impact on U.S. exports, leading to a collapse in many of the roughly 900 categories of targeted American products.

That slump came at a real cost to the U.S. economy. In calculations done for Bloomberg, the IIF economists found that between July and November of last year, the value of lost exports topped $17 billion, according to Sergi Lanau, the IIF's deputy chief economist. That's an annualized hit of about $40 billion, or almost a third of the $130 billion that the U.S. exported to China in 2017.