The NEG instruction negates a value by finding 2's complement of its single operand.
153 = 1 0 0 1 1 0 0 1,
its 2's compliment is 0 1 1 0 0 1 1 1
when negating Sign Flag(SF) will have 1 and Carry Flag(CF) is 0 because no carry is there.
So, AL = 0 1 1 0 0 1 1 1, CF = 0 and SF = 1