In landing the first big mandate from Sanofi since the French drugmaker switched chief executives, U.S. boutique Evercore Partners gets some $13 million of fees and a league-table boost.

On Thursday, Sanofi agreed to buy U.S. partner Merck & Co Inc out of their animal-health joint venture Merial for $4 billion.

Sanofi, advised by Evercore, gains control of treatments such as flea and tick product Frontline. Merck, which was counseled by Credit Suisse, needed the deal so regulators would approve its $41 billion tie-up with Schering Plough Corp.

Freeman & Co, a merger consultancy, reckons Evercore will receive $13 million to $15 million and Credit Suisse $14 million to $16 million for their work on the Merial deal.

That deal helped propel Evercore to an eye-catching 5th place in this year's U.S. mergers and acquisitions (M&A) league tables and 10th place globally, according to Thomson Reuters data.

The boutique, founded in 1996 by former Lehman Brothers and Blackstone Group banker Roger Altman, is credited with roles in just 14 deals this year.

However, these included advising Wyeth, alongside Morgan Stanley, on its $68 billion union with Pfizer, and work on the $61 billion sale of General Motors assets to a government-backed New GM.

Evercore's team on Merial included Francois Maisonrouge, the pharmaceutical-industry specialist who was previously chairman of life sciences at Credit Suisse, where he spent nearly 15 years. He joined Evercore in 2007.

Evercore and Maisonrouge declined to comment.

Healthcare bankers have circled Sanofi Chief Executive Chris Viehbacher since he took over in December, hoping to undertake some lucrative M&A business for the former GlaxoSmithKline Plc executive.

Clients are now realizing that big banks have demands that aren't completely aligned with their own interests, and many of these corporations have determined that it does not make sense to rely solely on M&A advice from the same banks that are providing the financing for a transaction, Maisonrouge said in a recent interview with the Financial News. Boutiques are well positioned to provide a role in such a case.

Viehbacher has not ruled out a mega-merger but wants to focus on small- and mid-sized deals, of up to about 15 billion euros, in generic drugs, emerging markets, vaccines, consumer health and biotech.

That potential openness to deals has led to Sanofi as being recently touted at as a possible buyer of Germany's Ratiopharm and Qiagen (QGEN.DE), Iceland's Actavis, Crucell of the Netherlands, and the drug business of Belgium's Solvay (SOLB.BR), among others.

Its second-biggest deal under Viehbacher, the 550 million euro takeover of unlisted Indian vaccines maker Shantha Biotechnics, was accomplished without financial advisers, a Sanofi spokesman said. Shantha's owners were advised by mid-market boutique Bryan, Garnier & Co.

(Additional reporting by Jessica Hall in Philadelphia; Editing Bernard Orr)