Treasury-backed bank NS&I has withdrawn guaranteed one-year growth and income bonds from the market after almost a quarter of a million people invested in just five weeks.
According to NS&I, over 225,000 people invested in the bonds over the five weeks from 30 August when they became available.
This "sheer number" is "unheard of", according to interactive investor analyst Myron Jobson.
“The NS&I has been a victim of its own success with its market-leading one-year fixed rate savings accounts," he said.
The bonds had offered interest at 6.20% as part of a one-year fixed agreement, placing them among the most highly rated on the market.
“This summer’s new one-year fixed-rate bonds have been a great success,” chief executive Darx Harkins said.
“I am pleased we were able to keep them on sale for over five weeks.”
NS&I, which is backed by the government and therefore entirely guarantees investments, has repeatedly lifted interest on its bonds this year in response to base rate hikes by the Bank of England.
As a result, the 6.20% offered on the one-year bonds was the highest ever offered on the product by the NS&I.
"This is another example that in a fast-paced, rapidly developing market where inflation is still hurting, you have to be on your toes," Jobson added.