European Central Bank

In a world where most emerging markets prefer to hunker down and hope that geopolitical turmoil passes them by, South Africa has done something almost audacious. The South African Reserve Bank raised its benchmark interest rate by a quarter percentage point to 7% per annum—the first rate hike in three years. The market responded not with panic or capital flight, but with strength. The rand gained 0.3%, reaching 16.32 per U.S. dollar. At a time when currencies across the developing world are falling under the pressure of the Iran conflict and a hawkish Federal Reserve, the rand has emerged as one of the few currencies capable of pushing back.

The South African Reserve Bank’s decision was anything but spontaneous. It was driven by economic data that could no longer be ignored. Inflation in South Africa is accelerating. Consumer prices rose 4% year-over-year in April, exceeding the central bank’s 3% target. That alone would be concerning. But the real shock came from producer inflation.

Data released on Thursday showed producer price inflation surging to 4.8% year-over-year. For comparison, the figure stood at just 2.3% in March. That represents more than a doubling in a single month. Producer prices are rising at an alarming pace, and those costs are likely to be passed on to consumers in the months ahead. The central bank saw the warning signs and chose to act before the problem intensified.

Raising interest rates is the traditional central-bank response to inflation. Higher borrowing costs cool demand, restrain price growth, and attract foreign capital. But the remedy comes with side effects: it can also suppress economic growth. At a time when South Africa is already grappling with high energy prices, supply-chain disruptions, and weak domestic demand, the rate hike...