The Sensex Tuesday opened 36 points lower on profit selling inblue chips like TCS and ICICI Bank. The 30-share index, which had gained 273 points in the previous session, fell by 36 points to 17,302 points. The wide-based National Stock Exchange index Nifty also shed 9.15 points to 5,189 points. Market men said cautious investors were seen booking profit after a recent surge in fundamentally strong stocks.