KARACHI : US dollar weakened slightly on Thursday and traded at the highest price of Rs 106.40 in cash free/open market. According to the details provided by the Forex Association of Pakistan, US dollar traded at the lowest price of Rs 105.48 and highest price of Rs 105.53 in inter-bank while it was traded at minimum prize of Rs 106.25 and maximum price of Rs 106.40 in cash free market.