To find the value decrease per month, you need to divide the total decrease in value by the number of months.
The total decrease in value is $4,000, and the number of months is 12.
\[ \text{Decrease per month} = \frac{-4000}{12} \]
Calculating that:
\[ \text{Decrease per month} = -333.33\overline{3} \]
Rounding to the nearest hundredth, we get:
\[ -333.33 \]
Therefore, the correct response is:
−$333.33