In a move heralded in Sullivan & Cromwell quarters as emblematic of the firm's role in helping women crack the glass ceiling, Goldman Sachs has announced that Sullivan partner Karen Seymour is joining the investment banking firm as co-general counsel and partner.

Seymour, who will take up the role in late January, will share responsibility for all of the investment bank's global legal matters with Goldman GC Gregory Palm, who is also a former Sullivan partner.

Seymour described her new role as an opportunity that "I wouldn't have even dreamed of as a goofy junior associate."

Since her early days practising law, Seymour has gained a wealth of experience in management, government and private practice. At Sullivan, Seymour served on the firm's management committee, and as co-managing partner of its litigation group. She has developed commercial litigation and white-collar criminal defence practices and defended individuals and institutions against allegations related to securities fraud, insider trading, and violations of the Foreign Corrupt Practices Act, among other things.

In 2015, she led the negotiations for BNP Paribas with the federal government leading to an $8.9bn settlement over allegations related to the bank's violations of sanctions against Sudan, Cuba and Iran.

Seymour also served two stints as a Manhattan federal prosecutor, serving as chief of the criminal division for the Southern District of New York and as lead trial counsel prosecuting and convicting US TV star and author Martha Stewart on obstruction of justice charges.

In 1993, she was working at the prosecutor's office when Mary Jo White, now senior chair of Debevoise & Plimpton, broke a glass ceiling and became the first woman to win the US attorney role for the Southern District of New York.

"Those kind of moves inspire hopefully everyone, but in particular junior women. They help us all dream big," Seymour said about White's appointment.

At Sullivan, a steady movement of its women partners to positions of power in the business world represents a source of pride and also strengthens the firm's relationships with financial services industry clients. In 2012, JPMorgan Chase tapped Stacey Friedman, a former Sullivan litigation and regulatory partner, as its GC.

Both JPMorgan and Goldman Sachs have assigned Friedman and Seymour respectively broad leadership roles. Friedman serves on JPMorgan's operating committee, and Seymour will serve as a member of Goldman's management committee.

"We are very proud that two of the world's leading financial institutions will have general counsels who were successful women partners at our firm," said Sullivan chairman Joe Shenker.