Shares of Delta Air Lines Inc. /zigman2/quotes/200327741/composite DAL +3.12% fell more than 8% in the extended session Friday after the airline said its second quarter will be "even more difficult than the first" and Warren Buffett's Berkshire Hathaway Inc. /zigman2/quotes/200060694/composite BRK.B +1.69% /zigman2/quotes/208872451/composite BRK.A +1.62% disclosed it sold chunks of Delta stock this week. Berkshire sold nearly 315 million shares on Wednesday and Thursday priced between $22.96 and $26.04, it said in a filing. Separately, Chief Executive Ed Bastian urged more employees to take extended leaves and said the company likely hasn't seen the bottom of the pandemic-related crisis. "This week we closed the books on the first quarter of 2020, and it was unlike any quarter in Delta's history," Bastian said in a memo to employees. The air carrier continued to see passenger volumes and revenues drop; in the past Saturday, it flew about 38,000 people, compared with a normal late-March Saturday around 600,000, he said. "Unfortunately, even as Delta is burning more than $60 million in cash every day, we know we still haven't seen the bottom," Bastian said. The company's April schedule will be about 80% smaller than planned, with 115,000 flights cancelled, Bastian said. Like other airlines, Delta said it submitted paperwork to benefit from government aid, but the funds alone "are not nearly enough" as Delta expects revenue to be down 90% for the second quarter. Without action, that money would be gone by June, he said. Delta asked employers to volunteer for unpaid leaves, including longer-term leave. The company also announced a 25% cut in hours for some employees, "essential to protecting Delta for the long term," the CEO said.