After six years of scrutiny, and repeated legal action against those around him, Steve Cohen remains a free man. His $15bn hedge fund SAC Capital is still in business and he still firmly maintains his innocence, despite the evident disbelief of regulators and prosecutors. It is time to prosecute him.

Mr Cohen may be innocent of insider trading, or he may be guilty, but a verdict should be reached in court. Cutting a deal behind closed doors to allow the US Department of Justice to claim victory without pinning Mr Cohen down would make a travesty of the biggest such case since Michael Milken was jailed for securities violations in 1990.

If he is innocent, his good name should now be restored to him. If he is guilty of running the most powerful insider trading operation on Wall Street for many years, he should be punished. The danger instead is that his reputation will be ruined without Wall Street or the public grasping what happened, or the lessons from it.