Sanofi Completes Acquisition of Bioverativ Inc. Bioverativ Inc. is a fully owned subsidiary of Sanofi Paris (France)

Sanofi Completes Acquisition of Bioverativ Inc.

Bioverativ Inc. is a fully owned subsidiary of Sanofi

Paris (France) March 8, 2018 Sanofi announced today the successful completion of its acquisition of Bioverativ Inc.

( Bioverativ ) for $105 per share in cash.

The addition of Bioverativ provides us with a strong position in the large

and growing hemophilia market and expands our presence in specialty care, said Olivier Brandicourt, Sanofi s Chief Executive Officer. Through a series of three strategic transactions the addition of Bioverativ, our planned

acquisition of Ablynx and our agreement for fitusiran we are well on our way to creating a leading franchise in the field of rare blood disorders.

The tender offer for all of the outstanding shares of Bioverativ common stock expired as scheduled at one minute after 11:59 p.m., New York City time, on

Wednesday, March 7, 2018. The minimum tender condition and all of the other conditions to the offer have been satisfied and on March 8, 2018, Sanofi and its wholly-owned subsidiaries, Sanofi-Aventis NA Holding, Inc. and Blink Acquisition

Corp. ( Purchaser ), accepted for payment and will promptly pay for all shares validly tendered.

Following its acceptance of the tendered

shares, Sanofi completed its acquisition of Bioverativ through the merger of Purchaser with and into Bioverativ, pursuant to Section 251(h) of the General Corporation Law of the State of Delaware, with Bioverativ continuing as the surviving

corporation and becoming an indirect, wholly-owned subsidiary of Sanofi. In connection with the merger, all Bioverativ shares not validly tendered in the tender offer have been converted into the right to receive the same $105 per share in cash

(without interest and net of any required tax withholding), that would have been paid had such shares been validly tendered in the tender offer. Bioverativ common stock will cease to be traded on the NASDAQ Stock Market.

Lazard acted as exclusive financial advisor to Sanofi. Guggenheim Securities and J.P. Morgan Securities LLC acted as financial advisors to Bioverativ. Weil,

Gotshal & Manges LLP served as legal counsel to Sanofi. Paul, Weiss, Rifkind, Wharton & Garrison LLP served as legal counsel to Bioverativ.

Sanofi is dedicated to supporting people

through their health challenges. We are a global biopharmaceutical company focused on human health. We prevent illness with vaccines, provide innovative treatments to fight pain and ease suffering. We stand by the few who suffer from rare diseases

and the millions with long-term chronic conditions.

With more than 100,000 people in 100 countries, Sanofi is transforming scientific innovation into

healthcare solutions around the globe.

Sanofi, Empowering Life

Forward-Looking Statements

This communication contains forward-looking statements. Forward-looking statements are statements that are not historical facts and may include projections

and estimates and their underlying assumptions, statements regarding plans, objectives, intentions and expectations with respect to future financial results, events, operations, services, product development and potential, and statements regarding

future performance. Forward-looking statements are generally identified by the words expects , anticipates , believes , intends , estimates , plans , will be and similar

expressions. Although Sanofi s management believes that the expectations reflected in such forward-looking statements are reasonable, investors are cautioned that forward-looking information and statements are subject to various risks and

uncertainties, many of which are difficult to predict and generally beyond the control of Sanofi, that could cause actual results and developments to differ materially from those expressed in, or implied or projected by, the forward-looking

information and statements. These risks and uncertainties include among other things, risks related to the successful integration of Sanofi and Bioverativ, that such integration may be more difficult, time-consuming or costly than expected or that

the expected benefits of the acquisition will not be realized, risks related to future opportunities and plans for the combined company, including uncertainty of the expected financial performance and results of the combined company, and the

possibility that, if Sanofi does not achieve the perceived benefits of the acquisition as rapidly or to the extent anticipated by financial analysts or investors, the market price of Sanofi s shares could decline, as well as other risks related

Sanofi s business, including the ability to grow sales and revenues from existing products and to develop, commercialize or market new products, competition, including potential generic competition, the uncertainties inherent in research and

development, including future clinical data and analysis, regulatory obligations and oversight by regulatory authorities, such as the FDA or the EMA, including decisions of such authorities regarding whether and when to approve any drug, device or

biological application that may be filed for any product candidates as well as decisions regarding labelling and other matters that could affect the availability or commercial potential of any product candidates, the absence of a guarantee that any

product candidates, if approved, will be commercially successful, risks associated with intellectual property, including the ability to protect intellectual property and defend patents, future litigation, the future approval and commercial success

of therapeutic alternatives, and volatile economic conditions. While the list of factors presented here is representative, no list should be considered a statement of all potential risks, uncertainties or assumptions that could have a material

adverse effect on Sanofi s consolidated financial condition or results of operations. The foregoing factors should be read in conjunction with the risks and cautionary statements discussed or identified in the public filings with the SEC and

the AMF made by Sanofi, including those listed under Risk Factors and Cautionary Statement Regarding Forward-Looking Statements in Sanofi s annual report on Form 20-F for the year ended December 31, 2017. The

forward-looking statements speak only as of the date hereof and, other than as required by applicable law, Sanofi does not undertake any obligation to update or revise any forward-looking information or statements.