This

Pronoun

  may

Auxiliary

  be

Auxiliary

  due to

 the

 preponderance  of

Adposition

 closet-index  funds

Noun

  in

Adposition

  the

Determiner

  study

Noun

.

This may be due to the preponderance of closet-index funds in the study.

This may be due to the preponderance of closet-index funds in the study.