Technically, -211% (-211.39%) is correct insofar as if B4=-6145, B4*(1+C5) = 6845.

Many people will say (correctly) that we cannot "increase" a negative number (i.e. become less negative or become positive) by multiplying by a positive percentage.

But I can understand why you might want to present that illusion. To do that, use the following formula:

=IF(B1=0, SIGN(B2), (B2-B1)/ABS(B1))

formatted as Percentage.

PS.... Many people will say (correctly) we also cannot increase or decrease zero by a percentage (B1=0). I threw that in because it is another common request. It based on the fact that if B1=1234 and B2=0, the normal result is correctly -100%.