Fallout from government investigations into controversial trades used by investors and banks to reduce taxes is mounting, with a London hedge fund recently closing and Bank of America’s European investment banking unit being pushed for information about the trades.

The request for detailed trading records from Bank of America's London-based Merrill Lynch International unit came in a December 19 letter from Globe Tax Services, a New York-based company that processes tax-refund paperwork for banks and investment firms. A copy of the letter, reviewed by The Wall Street Journal, was sent at the request of German tax authorities, according to a person familiar with the matter.