[peebee67]

Okay, so this is clearly corrupt, but is it illegal?

If not, add it to the United States Congress' many failings. If it is, since they spy on everything, it really shouldn't be hard to convict everyone who spilled the beans early. There's two halves to every transaction, and every trader probably told at least one other person, so there should be no shortage of people willing to rat on each other.