The Kwarteng plan puts at risk the very poorest people in the UK – and growth | Mohamed El-Erian

The government's policy approach risks stagflation. It is making history for all the wrong reasons

• Mohamed A El-Erian was chair of Barack Obama's Global Development Council

Friday, the day of Kwasi Kwarteng's fiscal event", was a day for the economic and financial history books, a day of eye-popping one-day moves in UK financial assets that should be of interest to more than traders, economists and economic historians. If sustained, the depreciation of the currency and the surge in sovereign borrowing costs will have important broad-based implications for the economic outlook. And once again, it is the most vulnerable segments of the population who are most at risk.

What was a generally difficult day for global markets was also a brutal day for UK financial assets. The 2% slump in stocks was accompanied by a 3% weakening in the value of sterling against the US dollar, bringing the total depreciation this year to around 20% and to a level last seen 37 years ago. Most historic of all was the surge in yields on UK government bonds, including the largest ever single-day rise in the five-year yield.

Mohamed El-Erian is president of Queens' College Cambridge. He was chair of President Obama's Global Development Council (2012-17) and is author of The Only Game in Town