BENGALURU, Nov 8 (Reuters) - Indian shares fell on Monday, weighed down by private banks and pharmaceutical stocks, while shares of Pfizer Inc's India arm jumped on positive data from the parent firm's experimental pill against COVID-19.

By 0505 GMT, the blue-chip NSE Nifty 50 index fell 0.26% to 17,871.10, while the benchmark S&P BSE Sensex was down 0.31% at 59,880.97.

The indexes have gained more than 25% this year on falling COVID-19 cases, the economy reopening and ample liquidity. They have, however, fallen from record highs on heavy foreign selling and concerns of overvaluation.

"If it (the market) consolidates here for some more time this is a good buying opportunity. Lots of companies have come out with very good results," said Samrat Dasgupta, chief executive at Esquire Capital Investment Advisors.

Of the 38 Nifty 50 companies that have reported September-quarter results so far, 21 have beaten estimates, Refinitiv Eikon data shows.

On Monday, shares of Pfizer Ltd gained as much as 8.3% after its parent said on Friday that its experimental COVID-19 antiviral pill cut by 89% the chance of hospitalization or death for adults at risk of severe disease.

That news sent shares in active pharmaceutical ingredient (API) maker Divi's Laboratories down as much as 8.8%. The company makes the API for generic versions of Pfizer rival Merck's COVID-19 antiviral pill molnupiravir.

The Nifty Pharma Index was down 1.83%.

The Nifty Private Bank Index was down 1.93%, as IndusInd Bank tumbled 12% after a media report on Friday said whistleblowers had alleged evergreening of loans at the lender's micro-finance arm.

Among other individual stocks, Eicher Motors extended gains for a second straight session after the truck and motorcycle maker reported a better-than-expected quarterly profit last week. (Reporting by Anuron Kumar Mitra and Gaurav Dogra in Bengaluru; Editing by Ramakrishnan M.)