HUNTINGTON BEACH, CA - APRIL 20: Oil pumpjacks stand at the Huntington Beach Oil Fields amidst the coronavirus pandemic on April 20, 2020 in Huntington Beach, California. Oil prices traded in negative territory for the first time as the spread of coronavirus (COVID-19) impacts global demand.   Mario Tama/Getty Images/AFP
== FOR NEWSPAPERS, INTERNET, TELCOS & TELEVISION USE ONLY ==
Oil prices entered into negative territory for the first time in April as supply exceeded demand. Getty Images/AFP  

How a software glitch in a broker's system led to heavy losses for oil traders