A federal jury in Chicago convicted two former traders of JPMorgan’s precious metals desk who had been charged with manipulating gold prices, finding they used misleading orders to rig prices.

The convictions are the capstone of a seven-year Justice Department campaign to punish a style of deceptive trading in futures markets known as spoofing. The rapid-fire strategy was prevalent at some Wall Street banks before Congress outlawed spoofing in 2010, and persisted even after its prohibition, according to prosecutors.