Citigroup mistakenly transferred $81 trillion to customers instead of $280, a blunder that was corrected within 90 minutes. The incident, which occurred in April last year, raised concerns about operational issues within the bank, as neither the remittance nor verification staff caught the error. This follows a previous mistake in 2020, where Citigroup erroneously sent $900 million to Revlon creditors, resulting in significant financial and reputational repercussions.