The answer to this can be found toward the end of Chapter 4. A search of Amazon’s paperback edition shows that it is on page 37. My own copy is on Kindle so I cannot verify that page number.
On page 37, Erik Larson describes how Dodd met with bankers at the offices of the National City Bank of New York. From them, he learned how much Germany owed to the United States and how little of the debt it was proposing to pay back. He learned that just two banks held more than $100 million in German debt. Germany was planning to pay back thirty percent of that money. The bankers were hoping that Dodd could at least persuade Germany not to openly default.
Dodd was not terribly sympathetic. He believed that the banks themselves were at fault for the extent of the debt. He believed that they never should have loaned out that much money. They should have realized that Germany was not a very good risk. Instead, he felt, they were so attracted by the chance to make a large profit that they took excessive risks. As Larson says,
The prospect of high interest rates on German bonds had blinded them to the all-too-obvious risk that a war-crushed, politically volatile country might default.
Thus, Dodd clearly believed that the banks bore the burden of the German financial obligation to the US.