Things have gotten so bad in South Africa that one of the fundamental laws of monetary policy is beginning to weaken, and even break.
A crippling energy crisis, a low growth environment and deteriorating fiscal metrics combined to push the rand to a record low last week.
But the normal response of raising interest rates to defend the currency may prove counterproductive, undermining a fragile economy and pushing the rand even lower, according to economists at Goldman Sachs International.
The South African Reserve Bank wants to support the rand to cut the cost of imports and ease pressure on inflation.
Tighter monetary policy risks "creating a feedback loop for the rand," Andrew Matheny and Bojosi Morule wrote in a note to clients.
"The risk of overtightening in the face of FX pressure is real and could ultimately undermine the SARB's policy response."
The rand on Friday reached 19.5148 per U.S. dollar amid diplomatic tensions over U.S. accusations that Pretoria helped ship arms to Russia.
That sent inflation expectations above the central bank's target range of between 3% and 6%.
It also stoked speculation over more interest rate hikes after the May 25 decision.
Matheny and Morule raised their forecast and now expect the central bank to deliver a 50 basis-point hike to 8.25%.
Cuts will only begin in the second quarter of 2024, they said.
The central bank has already delivered 425 basis points of tightening since November 2021, with March's bigger-than-expected 50 basis-point increase the latest move.
The central bank is now in a tough position, with rate increases and a pause to the tightening cycle both potentially undermining the rand.
"If the SARB doesn't hike, or even does a 25 basis-point hike, versus the market that is pricing in 50 basis points, we are likely to see some rand weakness," said Walter de Wet, an analyst at Nedbank.
The best policymakers can hope for is avoiding rand weakness, rather than strengthening the currency through rate hikes, he said.
"SARB is in a really tough position," said Win Thin, global head of currency strategy at Brown Brothers Harriman.
"Inflation and the weak rand warrant more rate hikes but the economy is already suffering from power shortages. I think they want to stop hiking soon but I'm not sure the market will let them."
The rand fell as much as 1.3% to 19.3215 per dollar in Johannesburg Wednesday.
It led the sell-off in emerging markets prompted by the U.S. debt drama and weak China data.
On Friday, however, the rand regained some ground in early trade on Friday as the dollar slipped ahead of a speech by U.S. Federal Reserve Chair Jerome Powell and an S&P rating review for South Africa later in the day.
At 08:46, the rand traded at 19.2800 against the dollar, around 0.2% stronger than its previous close.
Bloomberg