In a move expected for several months, Foster + Partners announced today that is expanding its shareholder base to include more employees as well as its first external investor, the private equity firm 3i. Although the London-based firm is remaining mum on how much the deal with 3i costs, the Financial Times reported earlier this week that it is worth between $800 million and $1 billion.

Lord Norman Foster founded his practice 40 years ago. In an interview yesterday with Tom Sawyer, an editor of Engineering News Record, RECORD’s sister magazine, the firm’s current financial director Gary Lawley said that the 71-year-old Foster will stay on as board chairman but will be less involved in day-to-day management. He will be supported by a new management board.

Additional changes announced today will expand the firm’s equity ownership to include all senior partners, which increases the number of senior management shareholders from four to fourteen. Additional shares have been reserved both for internal promotion and external recruitment purposes.

RECORD reported last month that an investor watchdog group is questioning Foster’s recent buyback of shares in an employee trust, which occurred prior to announced restructuring and deal with 3i. The Employee Share Ownership Centre wants to investigate how the trust was valued and whether or not all of Foster’s employees knew of its existence.