Barclays and four former senior executives are facing criminal charges relating to investment sought from Qatar at the height of the banking crisis.
The case dates back to 2008 when the bank's rivals - Lloyds and Royal Bank of Scotland - took state bailouts as the financial sector came under huge strain.
Emergency funds raised by Barclays at the time allowed it to avoid a government bailout.
The Serious Fraud Office (SFO) has capped a five-year investigation by announcing Barclays has been charged with two counts of conspiracy to commit fraud and the provision of unlawful financial assistance.
The charges centre on the bank's move to raise cash from Qatari investors Qatar Holding and Challenger Universal in June and October 2008, and a $3bn (£2.4bn) loan made available to the State of Qatar in November of that year.