When an Indian investor buys a US index fund, two things happen at once. The investor owns American companies, and the investor owns dollars. Most people only track the first.
Over the five years to October 2026, the S&P 500 rose about 68% in dollars. Measured in rupees, the same holding rose about 117%. Nothing about the companies changed between those two numbers. The difference was the dollar, which went from ₹74.79 to ₹96.78.
The long view
At the end of 2000, one dollar cost ₹46.75. At the end of 2025, it cost ₹89.87. That is an average fall of about 2.6% a year for the rupee over a quarter century. Measured over the last 20 years by fiscal-year averages, the figure is closer to 3.2% a year.
The main reason is inflation. India’s consumer prices have, on average, risen faster than America’s. When one country’s money loses purchasing power faster than another’s, the exchange rate tends to adjust to close the gap. Economists call this purchasing power parity. It is not a law that holds every month, but over decades it has held up well for the rupee.
Why this matters for your portfolio
If all your assets are in rupees, all of this is invisible to you, until you need dollars. A US university fee of $50,000 cost about ₹37 lakh in late 2021. Today it costs about ₹48 lakh. The fee didn’t rise. Your rupees bought fewer dollars.
A dollar asset works like a second return stacked on top of the investment return. In the years the rupee weakens, it adds to what you earn. It also tends to help most when you need it. In 2008, the S&P 500 fell 38% in dollars, but the rupee fell 23% against the dollar the same year, so an Indian investor holding it lost about 24% in rupees. The Nifty 50 fell 52%.
It doesn’t always work
The rupee does not fall every year. It strengthened in 2003, 2004, 2007, 2010 and 2017. In those years, dollar assets earned less in rupee terms than they did in dollars. Over any short period, the currency can work against you.
The RBI also manages the rupee actively, buying and selling dollars to smooth sharp moves. That slows big swings in either direction. Nobody can forecast the rate next year, and we don’t try.
How to think about it
- Don’t buy dollars as a bet. Currency moves are a side effect of owning global assets, not a reason on their own.
- Match dollars to dollar goals. If you expect to spend in dollars, on education, travel, property or family abroad, holding dollar assets removes a risk rather than adding one.
- Measure in rupees. Your life is priced in rupees. Always compare global returns in rupees, after the currency move, the way the ₹100 time machine does.
The point is not that the dollar will always rise. It is that a portfolio held entirely in one currency carries a risk most Indian investors never see on a statement.