Lloyd's broker Windsor is set to acquire the minority interests in Windsor Professional Indemnity (WPIL) for £9m.
In a statement Windsor revealed it has conditionally agreed to acquire the 45% economic interest in WPIL it does not already own.
The maximum consideration payable is £9m, which consists of an initial consideration of £4.5m in cash payable on completion.
The issue of the consideration shares will have a value of £500,000 and deferred consideration of up to £4m in cash.
Windsor chairman and chief executive David Low said: "I am delighted to announce the acquisition of the shares in WPIL which the group does not already own.
"The proposed acquisition provides the group with a strong platform to continue to develop the business, both organically and by acquisition in the future."