Deutsche Bank said it is exiting physical trading of precious metals as it scales back its securities unit to improve returns. Some parts of the business may be shifted to other units and the bank will continue to trade derivatives linked to precious metals. The move is part of an overhaul of the bank’s securities unit to help boost profitability and increase the proportion of capital on its balance sheet by shrinking assets. The decision was announced internally and will probably result in the loss of fewer than five jobs.