Nifty 50 and Sensex stock indexes opened lower on Tuesday, tracking Asian peers, as caution prevailed across global equities a day ahead of U.S. Federal Reserve Chair Jerome Powell's congressional testimony.

The blue-chip Nifty index fell 0.10 per cent to 18,739.10 as of 9:16 a.m. IST, while the benchmark S&P BSE Sensex lost 0.07 per cent to 63,123.17.