White & Case's role advising Saudi Aramco on its initial public offering hasn't been a secret for years. The scope of the firm's efforts, on the other hand, has remained under wraps until now.

In a Wednesday press release, the firm finally outlined some basic details of its work on the Saudi oil giant's $25.6 billion offering, naming key lawyers involved and providing an estimate of the attorney resources brought to bear: 400 White & Case lawyers across 20 of the firm's global offices.

The firm, which also advised Aramco on its $12 billion bond offering in April, has a long-term relationship with the Aramco that spans nearly seven decades, so it is no surprise that the firm is leading the charge as it goes through its IPO process.