Block said Thursday it's laying off more than 4,000 employees, or about half of its headcount. The stock skyrocketed more than 24% in extended trading. "Today we shared a difficult decision with our team," Jack Dorsey, Block's co-founder and CEO, wrote in a letter to shareholders. "We're reducing Block by nearly half, from over 10,000 people to just under 6,000, which means that over 4,000 people are being asked to leave or entering into consultation."Block CFO Amrita Ahuja said the job cuts wil...