Wall Street's overnight slump roiled most of the region's equity markets yesterday as investors dumped shares on fears that borrowing costs could be jacked up. 'There's some concern about rising rates,' a Singapore-based fund manager was reported as saying. Australia's main index slipped 1.2 per cent, Thailand's SET Index lost 3 per cent more and Singapore shares fell 0.9 per cent. Prices also retreated in Malaysia, Indonesia and New Zealand. Japanese stocks were marked down sharply in early trade on the US retreat but managed to claw back all of their losses by the close.