From Mr Mansoor Mohi-uddin.

Sir, Foreign exchange market participants should not be surprised that the dollar is rallying on the back of the crisis in US subprime mortgages ("Why now is a good time to sell the dollar", Barry Eichengreen, September 4). The currency is strengthening because US investors are repatriating funds from abroad to cover losses at home, while foreign investors are also having to buy dollars - first, to roll over their funding of mortgage investments, or second, to rebuild their US portfolios by acquiring less risky assets such as US Treasury bonds. These flows are resulting in the dollar rising against other major currencies such as the euro and sterling.