Passage
Consider the following code snippets and answer the given sub-questions.
```
M = [5, 8, 2, 4, 6, 9]
new_array = [M[i] + M[-(i % 3)] for i in range(len(M))]
print(new_array)
column_sum = 0
for i in range(len(new_array)):
column_sum -= new_array[i]
print(column_sum)
```