I have a question.

You changed the followiong sentence

"We need an experienced employee for managing portfolio."

into

"We need an experienced employee for the managing of our portfolio."

Why is artiticle "the" necessary in front of managing?  Which of the following is the most naturraL?

1.We need an experienced employee for the managing of our portfolio.

2. We need an experienced employee for managing our portfolio.

3. We need an experienced employee to manage our portfolio.

4. We need an experienced employee for the management of our portfolio.

Thank you in advance.

Yuchan