CBIZ shares rose 17.67% to $54.95 after Grant Thornton Advisors disclosed a $5 billion all-cash takeover proposal for the company. Under the terms of the deal, CBIZ stockholders would receive $55 in cash for each outstanding common share, a price that represents about a 54% premium to CBIZ’s 30-day volume-weighted average trading price.

The transaction, if completed, would create the fifth-largest professional services organization in the United States. CBIZ, Inc. (CBZ) was among the names mentioned in the announcement as the market reacted to the proposed acquisition.

Grant Thornton Advisors said it has reached a definitive agreement to acquire CBIZ. New Mountain Capital will provide additional equity capital to help finance the transaction, extending its support for Grant Thornton’s expansion strategy that began in May 2024. The private equity firm previously backed a move that accelerated Grant Thornton’s domestic footprint, and the new capital will support both the acquisition and future strategic initiatives for the combined organization.

CBIZ’s board of directors unanimously approved the merger agreement and recommended that shareholders vote in favor of the transaction. The companies said they expect the deal to close in the fourth quarter of 2026, subject to shareholder approval, regulatory clearances, and other customary closing conditions.

The merged company would be a U.S.-based business generating more than $5 billion in domestic annual revenue. It would also become the country’s fifth-largest provider of professional, tax, and advisory services. Grant Thornton said the transaction is the largest merger in the industry in the past 25 years.

Following completion, the expanded network would span more than 20 countries and territories. Combined annual revenue would approach $7.5 billion, and the organization would employ more than 34,500 professionals worldwide. Grant Thornton said the larger scale is expected to strengthen international service capabilities and broaden specialized expertise.

Grant Thornton also said it plans to roll out its technology infrastructure across CBIZ’s client portfolio. The firm recently committed $1 billion to artificial intelligence and other advanced technology initiatives, and it expects the combined organization to benefit through improved service quality, operational efficiency, and client engagement. For clients and competitors in the accounting and advisory market, the technology rollout and broader global reach highlight how the deal extends beyond ownership change and into how services may be delivered across a larger platform.

As part of the transaction structure, Grant Thornton intends to spin off CBIZ’s Benefits and Insurance Services division after the deal closes. New Mountain Capital would support that business as an independent company. The separated unit would focus on insurance, retirement planning, payroll administration, and related services.

CBIZ will be allowed to consider competing offers during a go-shop period that runs through August 27, 2026. During that window, the company’s financial advisers may solicit, evaluate, and discuss alternative proposals, and the board may accept a superior offer if one meets the terms of the merger agreement.

Once the acquisition is completed, Grant Thornton will own CBIZ outright. CBIZ shares will then stop trading and be delisted from the New York Stock Exchange. Until the transaction closes, CBIZ will continue operating as a public company under its current structure.