Sensex today declined by over 36 points in early trade due to profit-booking by speculators after recent gains amid mixed trend at the Asian markets.The 30-share barometer, which has gained over 64 points in the previous two sessions, fell by 0.21 per cent, to 17,426.74, with stocks of banking, realty and auto sectors succumbing to profit-booking.Similarly, the wide-based National Stock Exchange indexNifty fell by 12.55 points to 5,290.In the Asian region, Hong Kong's Hang Seng index was up marginally by 0.24 per cent, while Japan's Nikkei Index edged lower by 0.08 per cent. The US market remained closed yesterday for 'Independence Day' holiday.