BENGALURU, Nov 2 (Reuters) - Indian shares reversed course to fall slightly on Tuesday as pharmaceutical stocks lost their footing on the back of a slide in heavyweight Sun Pharma ahead of its quarterly earnings results later in the day.

By 0506 GMT, the blue chip NSE Nifty 50 index fell 0.15% to 17,902.25, while the benchmark S&P BSE Sensex was down 0.25% at 59,989.43.

"Typically, (the festive season of) Diwali week sees lower volume with a lot of traders on holiday... we normally don't see a big sell-off," said Deepak Jasani, head of retail research at HDFC Securities.

The Nifty and Sensex had shed 3.3% each over the final three sessions last week on concerns of overvaluations and heavy foreign selling, before recouping some of those losses on Monday with gains of more than 1%.

On Tuesday, the Nifty Pharma Index fell 0.69%, snapping two straight sessions of losses, as Sun Pharma slipped 2.3% to be the biggest loser on the Nifty 50. The company is due to report September-quarter earnings later in the day.

Limiting losses, however, was the Nifty Auto Index gaining 1.41%. Shares of Tata Motors rose as much as 5% after the carmaker projected pre-tax earnings margin and free cash flow at its Jaguar Land Rover unit to turn positive in the second half of fiscal 2022.

The Nifty Realty Index rose 2.86%, extending gains for a third session.

Among other stocks, agrochemical holding company PI Industries shed 7.6% after its deal with active pharmaceutical ingredient maker IND Swift Laboratories fell through.

Joining a long list of Indian startups that have tapped the capital market this year, logistics firm Delhivery Ltd filed for an initial public offering of up to 74.6 billion rupees.

($1 = 74.8050 Indian rupees) (Reporting by Anuron Kumar Mitra in Bengaluru; Editing by Ramakrishnan M.)