Bank of America Merrill Lynch is nursing a multi-million euro hit on an unsuccessful block trade of shares in Deutsche Post, according to sources familiar with the matter, and may be holding about €300m of unwanted stock in the German mail provider.

The US bank last week won the mandate to sell €924m worth of Deutsche Post shares on behalf of the German government. KfW, the state-owned development bank behind the sale of the holding, had invited a number of investment banks to pitch for the job of underwriting and selling the stock into the market.