The rupee today depreciated by 13 paise against the US dollar in opening trade. At the Interbank Foreign Exchange (Forex) market, the domestic unit traded at 46.24 a dollar. It had closed 27 paise higher at 46.11 against the dollar yesterday after the Sensex ended marginally up by 16 points. Forex dealers said fears that foreign funds would exit domestic bourses following a weak pattern in other Asian markets weighed heavily on the rupee sentiment.