Stock market benchmark indices Sensex and Nifty tumbled in early trade on Thursday as the additional 25 per cent tariff imposed by US President Donald Trump on India for its purchases of Russian oil came into effect, weighing on investors' sentiment. Besides this, foreign fund outflows also dented investors' sentiment.

The additional 25 per cent tariff imposed by the US on India came into effect on Wednesday, bringing the total amount of levies imposed on New Delhi to 50 per cent.

Both the benchmark indices, Nifty 50 and Sensex, remained under pressure through the opening session.