Three London-based employees at the centre of JP Morgan's multibillion-dollar trading blunder, including one known as the "London whale," have left the bank, according to people familiar with the company.

Achilles Macris, Javier Martin-Artajo and Bruno Iksil are the latest casualties of an episode that already has cost the bank $25bn in market value and tarred the reputation of chief executive James Dimon as Wall Street's savviest risk manager.