Oil traders struggling to navigate one of the biggest oil crashes in history say the worst is yet to come. Even after plunging about 60% this year to the lowest since 2003, prices will likely drop further to $20 a barrel or below, according to a survey of traders from some of the world’s biggest oil companies and merchants. Analysts from Goldman Sachs Group Inc. to Citigroup Inc. also expect prices to extend declines in the coming months, with some even speculating certain regional prices could go negative as markets try to send signals to halt supply.Oil has been battered by the simultaneous fight against Covid-19, which is expected to reverse more than a decade of global demand growth, and a flood of supply as Saudi Arabia and Russia battle for market share. The sudden and severe plunge in oil prices has helped fuel the broader sell-off across markets, and threatens economies across Latin America and the Middle East, as well as the U.S., where the energy industry accounts for large chunks of both output and debt.