In Capital IQ:

Enter company name into the search box.

Select Competitors from the menu on the left (near top under Company Summary).

In Mergent Intellect:

Enter company name or ticker into search box.

Select Competitors tab.

(For early stage companies) In Pitchbook:

Use the Similar Companies feature.

In Factiva:

Select Company from the Companies/Markets drop-down menu at top of screen.

Enter company name or symbol  into the search box.

Select Peer Comparison from the menu on the left.