Robert Diamond, the architect of Barclays Plc's investment banking expansion, stepped down as chief executive officer, succumbing to political pressure to go after the bank admitted to rigging global interest rates.

Diamond, 60, will resign immediately, the London-based bank said in a statement today, a day before he faces questions by British lawmakers. Diamond became CEO of Barclays on Jan. 1, 2011 after joining the bank in 1996. Marcus Agius, who said yesterday he planned to step down, will become full-time chairman and lead the search for a new CEO.

Barclays was hit by a record 290 million-pound ($455 million) fine last week for rigging the benchmark for more than $360 trillion of securities. Diamond had yesterday defied pressure to quit, pledging to implement the findings of a review into how the bank sets the London interbank offered rate.