Jack Dorsey says he's cutting nearly half of his staff — 4,000 jobs — at Block. Read the memo.

Block is letting go of over 4,000 employees, cutting the company nearly in half, cofounder and CEO Jack Dorsey said Thursday. "I had two options: cut gradually over months or years as this shift plays out, or be honest about where we are and act on it now. I chose the latter," Dorsey, who also …