A former financial consultant for the Halifax Bank left an IOU note for £7m in a branch safe, a court has heard.
Graham Price was remanded on bail
Graham Price, of Llansamlet, Swansea, admitted 43 charges of theft and asked for a further 263 offences relating to a £10m scam to be taken into account.
The 58-year-old stole cash from the bank and dozens of investors while working at the Gowerton branch office.
He was released on conditional bail and the case was adjourned for sentencing at Swansea Crown Court on 7 November.
Linda Baker, prosecuting, told magistrates in Swansea on Tuesday that Price began taking money from the safe and stealing from investors' accounts in January 2001.
She said the offences, carried out over four years, were premeditated acts which all represented a breach of trust.
But Price was caught out when an unannounced cash audit was carried in November last year.
When Halifax auditor Lesley Tucker opened the safe he found only three empty boxes and a scrap of paper, Mrs Baker said.
Price had written and signed a note declaring 'I have borrowed £7m from the Halifax'.
He stole £3m of the money over just a nine-day period last summer, the hearing was told.
Mrs Baker said: "It appears that over a period of time he was removing money from the safe and taking it from investors."
Price disappeared after the Halifax discovered money was missing but he was traced and arrested.
Asked whether he admitted the charges Price told the court: "Each and every one."