In paying the highest-earning equity partners more than $20 million, or around nine times more than their lowest-paid counterparts, Simpson Thacher & Bartlett joined a handful of peer Am Law 50 firms that can compete for the industry’s most successful rainmakers.

A decade ago, it would have been “unheard of” to pay partners that much, said consultant Peter Zeughauser, chair of the Zeughauser Group.