The rupee today again breached 68 mark by plunging 92 paise to 68.55 against the US dollar in early trade, mainly on strong demand for the American currency from importers and some banks. Dealers said heavy capital outflows amid reports that S&P sees more than one-in-three chance of a downgrade of the country's rating and dollar's gain against some overseascurrencies on upbeat economic data weighed on the domestic unit.