Chief executive Stephen Hester said the bank – which is mainly owned by the British government – would see its market capitalization wiped out if current reform plans progress.
Speaking at Manchester Business School yesterday, he said: “Economic recovery is proving slower and more challenging and the market and regulatory environment has changed even more dramatically than we bargained for.
“The UK regulatory reforms on their own have probably cost £10bn to £20bn from our future market value.”
Hester said reforms set out by the Independent Commission on Banking (ICB) would further restrict the bank’s growth, the Telegraph reported.
The bank is currently valued at about £25bn.