A consortium led by the Carlyle Group LP (Nasdaq: CG) has closed on a deal for New York investment banking firm Duff & Phelps Corp. for about $665.5 million.

The group includes Carlyle, Stone Point Capital LLC, a private equity firm headquartered in Greenwich, Conn., Pictet & Cie, a Swiss asset manager, and funds managed by Luxembourg-based Edmond de Rothschild Group. The target hopes to expand its international presence.

The deal was announced in December, but Duff & Phelps had until Feb. 8 to solicit better and higher offers. If it had not gone through with the deal, it would have had to paid the group break-up fee of $6.65 million.

The deal gave Duff & Phelps stockholders $15.55 per share. The company’s shares closed at $13.05 on Dec. 28.

Centerview Partners acted as Duff & Phelps’ financial adviser, while Kirkland & Ellis provided the company with legal advice. Sandler O’Neill & Partners LP, Credit Suisse, Barclays and RBC Capital Markets provided financial advice to the consortium, while Wachtell Lipton Rosen & Katz served as legal counsel.