New Delhi, June 10 -- The Nifty 50's 10-year-long winning run faces a crude challenge. Already down 11% on a year-to-date basis and with no end in sight to the headwinds being faced by the Indian stock market, the benchmark Nifty index could post its first annual decline after a decade of back-to-back positive yearly gains.

This poses a unique challenge for investors for whom index funds make up a large chunk of their portfolios.

This year's underperformance on Dalal Street comes due to the sharp spike in global crude oil prices following the Middle East conflict between the US and Iran, which is in its fourth month. From a sub-$68 per barrel level, Brent crude futures have risen to almost $92 currently. At one point, prices had touched...