The US dropped two 2,000-pound (900-kilogramme) bombs on Sunday in central Mosul destroying the building containing huge amounts of cash, CNN quoted two American defence officials as saying.
The officials could not say exactly how much money was there or in what currency, but one described it as "millions."
The officials said the US plans to strike more financial targets like this one to take away ISIS's ability to function as a state-like entity.
The defense official said the coalition had targeted cash-holding facilities once or twice in the past year, but Sunday's action was "probably" the biggest to date.
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The US considers the Mosul strike extremely sensitive, as the building is in an area where civilians are also located, and there was a significant risk of civilian casualties.
Officials would not say how the US learned of the location. But after getting intelligence about the so-called "cash collection and distribution point," US aircraft and drones watched the site for days trying to determine when the fewest number of civilians would be in the area.
US commanders had been willing to consider up to 50 civilian casualties from the airstrike due to the importance of the target. But the initial post-attack assessment indicated that perhaps five to seven people were killed, the report said.