Pre-war and early-war commercial dealings with Germany, operations of foreign branches in occupied Europe, and the Bank for International Settlements (BIS):
US side:
Chase National Bank (predecessor of JPMorgan Chase) participated in the Rückwanderer Marks program from 1936 to 1941. It sold discounted German marks—drawn largely from blocked accounts of Jews who had fled Germany—to German-Americans planning to return, generating more than $20 million in foreign exchange for the Reich and roughly $500,000 in commissions for Chase. FBI documents later confirmed the scheme. After the German occupation of France, Chase’s Paris branch remained open, handled Reichsbank and German Embassy accounts, preemptively blocked Jewish customers’ assets, and saw deposits roughly double with German-linked funds. New York headquarters was informed but did not intervene. Similar patterns occurred at J.P. Morgan’s French operations. In the late 1990s Chase reached a settlement with Jewish organizations and submitted to an independent review of its wartime French activity.
en.wikipedia.org
The Union Banking Corporation in New York, whose directors included Prescott Bush (father of George H. W. Bush) partners from Brown Brothers Harriman, served as a vehicle for the Thyssen family’s U.S. interests. Fritz Thyssen had provided early financial support to the Nazi Party. U.S. authorities seized UBC assets in 1942 under the Trading with the Enemy Act; they were later returned.
en.wikipedia.org
On the British side, the Bank of England authorized the March 1939 transfer of 23.1 tonnes of Czechoslovak gold held in a BIS account at Threadneedle Street to a Reichsbank account after the German occupation of Prague. Governor Montagu Norman approved the move on banking-procedure grounds. A second, larger transfer of Czech gold was blocked by the Treasury. Barclays’ Paris branch volunteered the names of Jewish staff to German administrators, accepted a deposit of funds taken from prisoners at the Drancy transit camp, and helped arrange credit for a quarry expansion intended to increase output for the German war effort. Pre-war British commercial banks also extended loans to German borrowers under standstill arrangements; at the outbreak of war those outstanding credits totaled about £34 million.
smh.com.au
The BIS (Bank of International Settlements), owned by central banks including the Bank of England, transferred the Czech gold, accepted 3.7 tonnes of looted Belgian and Dutch gold from the Reichsbank during the war, and continued to receive interest payments from Germany that were used to pay dividends to its shareholders. Reichsbank vice-president Emil Puhl described the BIS as Germany’s “only real foreign branch.” After the war the BIS restituted a portion of the looted
gold.bis.org
These transactions occurred in a period when the United States remained formally neutral until December 1941 and when international payments still flowed through established correspondent networks and the BIS. Direct wartime lending by British or American banks to the German government after hostilities began was illegal and limited; most documented activity involved occupied-territory branches, gold transfers, or pre-war credits. Post-war investigations and 1990s–2000s settlements addressed frozen Jewish accounts and some looted assets, but prosecutions of the banks themselves were rare.