New Delhi, Jan. 8 -- The Indian rupee briefly touched its international dialling code-91-against the dollar in mid-December 2025. It has since pulled back, but the so-called "nervous nineties" understandably make investors uneasy about where the rupee is headed next. The retreat from the all-time low beyond 91 was reportedly aided by Reserve Bank of India (RBI) intervention, with the central bank supplying dollars to the system.

To put the recent weakness in perspective, consider the pace of depreciation over time. Around 2000, the rupee was near 45 to the dollar. Over the past 25 years, it has depreciated at roughly 3% a year. Look further back, however, and the picture changes. In 1975, the rupee stood at about 10 to the dollar. From t...