Wall Street’s top regulator on Friday dropped its civil case against two JPMorgan Chase traders who attempted to hide the infamous $6.2 billion “London Whale” trading loss.

The Securities and Exchange Commission decided to stop pursuing charges against Javier Martin-Artajo and Julien Grout after a third trader, a witness in the case, recently changed his story.

The unexpected twist forced prosecutors to drop their criminal case against Martin-Artajo and Grout. The third trader laid more of the blame on JPMorgan CEO Jamie Dimon.

Bruno Iksil, aka The London Whale, a London-based trader, had borne the brunt of most of the super-size losing trades, which earned him the scornful nickname.

The bank was essentially on the wrong end of a complicated debt investment.

Iksil’s testimony — and subsequent public comments — led to the Justice Department dropping its criminal case against Martin-Artajo and Grout last month.

A JPMorgan spokeswoman declined to comment.