Sullivan & Cromwell spends millions of dollars on technology, ensuring its equipment is accessible to its lawyers around the globe and that its digital security can keep clients safe. Chairman Joe Shenker, citing bank surveys, says the Wall Street firm's tech costs per lawyer are higher than any of its peers.

Still, Sullivan & Cromwell has managed to improve its profit margin while maintaining high-quality telecommunications, computers and servers. That financial success isn't tied only to the firm's lawyers. It's partly a result of back-office decisions.

Starting in 2017, the firm began outsourcing some of its technology functions and infrastructure. The change required about 30 high-level staffers, including engineers, to leave the firm and become employees of another business, HBR Consulting's managed services division.