THESE are glorious days at Recep Tayyip Erdogan Stadium, a tidy 14,000-seat football ground perched on a steep hillside in the Kasimpasa district of Istanbul—and named after a local lad who became president. Kasimpasa SK are top of the Super Lig, Turkey’s top division, having won their first four games of the season.

The economy over which Mr Erdogan presides, by contrast, is embroiled in a battle for survival. This year the lira has fallen by 40% against the dollar, tumbling especially hard last month after a diplomatic row with America. Inflation is nearly 18%. The central bank, pressed by Mr Erdogan to keep interest rates down, has been slow to react, but on September 13th, even as the president urged a cut, it raised its policy rate by 6.25 percentage points, much more than markets had expected, to 24%. The lira leapt in response.

Turkey’s economy is already slowing sharply. Year on year, growth fell from a breakneck 7.4% in the first quarter to 5.2% in the second. GDP may shrink in the closing months of 2018. The credit that fuelled the boom—much of it from abroad, pushing the current-account deficit to 6% of GDP—is drying up. Adjusted for inflation, bank lending is declining. Even big companies are being quoted borrowing rates of 35%.

Such a sudden halt often spells trouble for banks. Warning signs are flashing. Listed banks’ share prices...