This week has been a tumultuous one for the global financial sector, as regulators face a reckoning over a series of banking collapses that have left investors reeling.

The turmoil began on Monday when the U.K.’s largest lender, Barclays, announced that it was in the process of winding down operations in a move that stunned the markets. The bank had been struggling to adapt to a low-interest rate environment and had recently announced a £1.5 billion ($2 billion) loss for the first quarter of the year.

The news sent shockwaves through the markets, as investors began to question the stability of the banking system. The U.K.’s Financial Conduct Authority (FCA) quickly stepped in, launching an investigation into the bank’s collapse and demanding answers from Barclays’ executives.

The FCA’s investigation has now led to the resignation of Barclays’ CEO Jes Staley and the promise of an independent review of the bank’s operations.

The financial crisis continued to escalate on Tuesday when another U.K. lender, the Royal Bank of Scotland (RBS), announced that it too was facing difficulties. The bank reported a £1.2 billion ($1.6 billion) loss for the first quarter of the year, and warned that its long-term outlook was uncertain.

The news sent further shockwaves through the markets, with investors now questioning the stability of the entire banking system. The FCA has since launched an investigation into the RBS and has called for an independent review of the bank’s operations.

The financial crisis has now spread to other parts of the world, with U.S. banking giant Citigroup announcing on Wednesday that it was also facing difficulties. The bank reported a $3 billion loss for the first quarter of the year, with chief executive Michael Corbat warning that the bank’s long-term outlook was uncertain.

The news sent further shockwaves through the markets, with investors now questioning the stability of the entire banking system. The U.S. Federal Reserve has since stepped in, launching an investigation into the bank’s collapse and demanding answers from Citigroup’s executives.

The financial crisis has now reached a tipping point, with regulators across the world facing a reckoning for their role in allowing the banking system to reach such a precarious state. The FCA, the Federal Reserve, and other regulators must now answer for their actions and explain why they failed to take action sooner to protect the global financial system.

The repercussions of the banking crisis are likely to be felt for some time, with investors now questioning the stability of the entire banking system. Regulators must now take steps to ensure that such a crisis cannot happen again and that investors are protected in the face of future shocks.