LETTER TO SHAREHOLDERS #46

SEPTEMBER 2016

04 - NEWS: SANOFI AND BOEHRINGER INGELHEIM HAVE REACHED DEFINITIVE AGREEMENTS FOR BUSINESS SWAP

07 - CALL FOR CANDIDATES: PARTIAL REAPPOINTMENT OF THE INDIVIDUAL SHAREHOLDERS COMMITTEE06 - SHAREHOLDER INFORMATION: INDIVIDUAL SHAREHOLDERS COMMITTEE

02 - INTERVIEW WITH THE CHIEF EXECUTIVE OFFICER « WE HAVE MADE STRONG PROGRESS ON OUR OBJECTIVE OF RESHAPING THE PORTFOLIO » 05 - NEWS: APPROVALS AND PROGRESS IN RESEARCH & DEVELOPMENT

2 - SANOFI LETTER TO SHAREHOLDERS #46 SEPTEMBER 2016- -

AGGREGATE COMPANY SALES 1,2

E8,868M -0.2% (- 4.3%)

BUSINESS NET INCOME 1

E1,680M-3.3% (-8.7%)

BUSINESS EPS 1,3

E1.31-2.1% (-7.1%)

RESULTS

MESSAGE FROM THE CHAIRMAN

OLIVIER BRANDICOURT, CHIEF EXECUTIVE OFFICER

SERGE WEINBERG, CHAIRMAN OF THE BOARD OF DIRECTORS

DEAR SHAREHOLDERS,

During the first half of 2016, our company continued its efforts to achieve its main strategic goals: reshape its portfolio, deliver outstanding launches of new products and sustain innovation in Research & Development.

Recent highlights include the approval of the Diabetes treatment Adlyxin™ in the United States and the submission of the marketing authorization application for sarilumab, a promising investigational treatment in rheumatoid arthritis.

We also achieved a new key milestone to reshape our portfolio. As you may know, we decided to refocus our businesses on human health, without abandoning diversification which we think is important to give our company a solid foundation and a limited risk profile. When we signed the agreement with Boehringer Ingelheim, we decided to strengthen our Consumer Healthcare business by swapping our Animal Health business. By the end of this year, the expected closing of the transaction will lift us into a global leadership position in the large and growing Consumer Healthcare market thanks to the complementarity of both product portfolios.

Oncology is another area where we plan to rebuild a competitive position. Our pursuit of the U.S. based biopharmaceutical company Medivation eventually did not succeed. However, we will continue in our efforts to strengthen our position in Oncology, which is one of the largest and fastest growing therapeutic areas in the biopharmaceutical sector.

Thank you for your trust and continuing loyalty.

DIVERSIFICATION IS IMPORTANT TO GIVE SANOFI A SOLID FOUNDATION AND A LIMITED RISK PROFILE.

INTERVIEW WITH THE CHIEF EXECUTIVE OFFICER

SECOND QUARTER 2016 RESULTS

SANOFI - LETTER TO SHAREHOLDERS #46 - SEPTEMBER 2016 - 3

RESULTS

❚ WHAT ARE THE HIGHLIGHTS OF THE SECOND QUARTER 2016?

Our 2nd quarter results are in line with expectations and reflect some of the headwinds we anticipated from the situation in Venezuela and Plavix® loss of exclusivity in Japan in June 2015. Sales were slightly down to €8.9bn, but up 1.9% at CER excluding Venezuela. Business EPS also declined by 2.1% at CER. Importantly, this is the last quarter we will be seeing the negative impact from the Venezuela currency situation and the Plavix® loss of exclusivity impact will be diminished in the second half of this year.

Sanofi Genzyme remained our fastest growing business driven by our Multiple Sclerosis and Rare Diseases franchises. Sanofi Pasteur performed well despite a delay in Dengvaxia® uptake. In addition, we made further solid progress with the launches of Toujeo® in a competitive Diabetes market and Praluent® which gained market share in the U.S. and was recently approved in Japan for the treatment of hypercholesterolemia.

❚ WHAT PROGRESS HAVE YOU MADE WITH THE RESHAPING OF YOUR PORTFOLIO AND R&D ACTIVITIES?

We have made strong progress in both areas. We signed the Consumer Healthcare asset swap with Boehringer Ingelheim in June, and expect to close by the end of the year.1

Concerning innovation, we enlarged our offer in Diabetes with the approval in the U.S. of Adlyxin™, which is also known as Lyxumia® in other countries.

WE REMAIN FOCUSED ON IMPLEMENTING OUR 2020 STRATEGIC ROADMAP AND HAVE MADE STRONG PROGRESS ON OUR OBJECTIVE OF RESHAPING THE PORTFOLIO.

We also made progress with our Immunology pipeline. We submitted sarilumab for approval to health authorities in Europe and the U.S. in rheumatoid arthritis.

❚ YOU MENTIONED THE DELAY IN DENGVAXIA® UPTAKE?

In Latin America, four news registrations2 were recently granted and Brazil announced the launch of its first public vaccination program in the State of Paraná. Despite these encouraging developments, the overall uptake of Dengvaxia® is delayed by recent political changes and economic volatility in Latin America. In Asia, the vaccine is available in the Philippines, and was recently approved in Indonesia.

❚ SALES IMPACTED BY EXCHANGE RATE MOVEMENTS

In the second quarter of 2016, aggregate company sales were €8,868M, down 4.3% on a reported basis. Exchange rate movements had a negative effect of 4.1 percentage points with the adverse evolution of the U.S. dollar as well as several emerging market currencies. At constant exchange rates (CER) aggregate company sales were down 0.2%.

This performance included a negative currency impact related to the change of exchange rate applied for the translation of operations in Venezuela which is going through a deep economic crisis. In addition, in the second quarter of 2015, Sanofi benefited from a significant increase in product demand in Venezuela. As a consequence, sales in Venezuela were €199M in the second quarter of 2015 compared to €6M in the second quarter of 2016. Excluding Venezuela, aggregate company sales increased 1.9% at CER in the second quarter of 2016.

❚ PERFORMANCE SUPPORTED BY GROWTH OF SPECIALTY CARE, VACCINES AND ANIMAL HEALTH FRANCHISES

Specialty Care maintains a positive momentum, supported by the strong performance of the Multiple Sclerosis franchise, up 67.3% at CER thanks to the growth of Aubagio® and Lemtrada® sales. The double-digit sales growth (14.2% at CER) of the Rare Diseases franchise also contributes to the strong momentum.

Consolidated Sanofi Pasteur sales were up 6.3% at CER, notably driven by the Polio/Pertussis/Hib vaccines in Emerging Markets.

Animal Health sales were up 9.1% at CER, driven by the success of NexGard® family of products, Merial’s next generation flea and tick products for dogs, in the U.S., Europe and Japan.

1 - Growth rates are expressed at constant exchange rates (CER). Growth rates in brackets are expressed on a reported basis. For definitions of financial indicators, please consult the press release issued on July 29, 2016.2 - Including Animal Health Business which is reported on a single line in the consolidated income statements in accordance with IFRS 5 (Non-current held for sale and discontinued operations). 3 - Earnings per share.

Sales by franchise Q2 2016 Change at CER

Specialty Care €1,493M +19.5%

Diabetes & Cardiovascular €1,962M -2.0%

Established Products €2,617M -9.7%

Consumer Healthcare €800M -4.3%

Generics €474M -1.9%

Vaccines €797M +6.3%

Animal Health €725M +9.1%

Lisa, multiple sclerosis, United States

According to the Multiple Sclerosis Foundation, there are approximately 2.5 million people living with multiple sclerosis worldwide.

This disease is 2 to 3 times more common in women.

1 - Subject to regulatory clearances in different countries.2 - Costa Rica, Paraguay, Peru, Guatemala.

4 - SANOFI - LETTER TO SHAREHOLDERS #46 - SEPTEMBER 2016

SANOFI AND BOEHRINGER INGELHEIM HAVE REACHED DEFINITIVE AGREEMENTS FOR BUSINESS SWAP

MAJOR MILESTONE BEFORE CLOSING OF TRANSACTION EXPECTED BY YEAR-END 20161

Sanofi and Boehringer Ingelheim (BI) signed contracts to secure the strategic transaction initiated in December 2015 which consists of an exchange of Sanofi’s Animal Health business and BI’s Consumer Healthcare (CHC) business.

Upon successful complet ion, BI’s CHC business (enterprise value of e6.7bn) would be transferred to Sanofi and Sanofi’s Animal Health business (enterprise value of e11.4bn) would be transferred to BI. The transaction includes a cash payment to Sanofi of e4.7bn to reflect the difference in value of the two businesses.

COMPLEMENTARY CHC PORTFOLIOS

With this transaction, Sanofi would integrate BI’s CHC business in all countries except

1- Subject to r egulatory clearances in different countries

2- Excluding Venezuela3- Nicholas Hall & Compan y, FY 2015,

excludes BI CHC in China4- CIS , Middle-East Africa and South Asia.

NEWS

BUILDINGGLOBAL LEADERSHIP IN CONSUMER HEALTHCARE IN LINE WITH OUR STRATEGY.

RANKING OF CONSUMER HEALTHCARE

BUSINESS IN KEY REGIONS

Evolution based on combined

Sanofi and BI CHC sales 3

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Europe: #4 ➜ #1Latin America: #1 (no change)

Asia-Japan-Pacific: #8 ➜ #2Rest of world 4: #2 (no change)

North America: #7 ➜ #6

China. Joint CHC sales would amount to approx. e4.9bn2 based upon 2015 global sales.

T h a n k s t o t h e a d d i t i o n o f a h i g h l y complementa r y p roduct and b rand portfolio, Sanofi would enhance its position in several of its strategic categories – Pain Care, Al lergy Solut ions , Cough & Cold Care, Feminine Care, Digestive Health and Vitamins, Minerals and Supplements.

The transaction would also expand Sanofi’s CHC scale in key geographic regions , in particular in Europe and the Asia-Japan-Pacific regions (see box.)

NEWS

LAUNCH OF FIRST DENGUE IMMUNIZATION PUBLIC PROGRAM IN BRAZIL First dengue immunization public program in the Americas started at the beginning of August in Brazil, in Paraná State. Paraná will lead dengue prevention in Brazil with this benchmark public program initiated to immunize 500,000 individuals with Dengvaxia® dengue vaccine over the next three weeks.

Paraná State, home to 10 million people, has seen a steep 3-fold increase in both dengue incidence and deaths in recent years.

APPROVALS AND PROGRESS IN RESEARCH & DEVELOPMENT

❚ ADLYXIN™ APPROVED IN THE UNITED STATESFOR THE TREATMENT OF TYPE 2 DIABETES

At the end of July, the U.S. Food and Drug Administration (FDA) approved Adlyxin™ (lixisenatide), a once-daily mealtime GLP-1 receptor agonist injection, indicated as an adjunct to diet and exercise for the treatment of adults with type 2 diabetes.

Adlyxin™ is approved under the proprietary name, Lyxumia® in more than 60 countries and marketed in over 40.

❚ NEW DRUG APPLICA TION FOR INVESTIGATIONAL FIXED-RATIOCOMBINATION OF INSULIN GLARGINE AND LIXISENATIDE

On May 25, 2016, the FDA Advisory Committee recommended the approval of the investigational once-daily fixed-ratio combination of basal insulin glargine and lixisenatide (known under the project name LixiLan) for the treatment of adults with type 2 diabetes.

On August 19, Sanofi announced the submission of updated information on the pen delivery device as part of the New Drug Application for the fixed-ratio combination. The company looks forward to hearing from the FDA once the review of the updated information has been completed.

❚ PRALUENT® APPROVED IN JAPAN FOR THE TREATMENTOF HYPERCHOLESTEROLEMIA

Sanofi and Regeneron announced at the beginning of July that Praluent® was granted marketing and manufacturing authorization in Japan. In this country, Praluent® is indicated for the treatment of patients with hypercholesterolemia and familial hypercholesterolemia who are at high cardiovascular risk and in whom treatment with statins is not sufficient.

❚ POSITIVE PHASE III RESULTS FOR DUPILUMAB IN ATOPICDERMATITIS

Results from the Phase III study CHRONOS demonstrated that a treatment with dupilumab used with topical corticosteroids was superior to a treatment with topical corticosteroids used alone in patients with moderate to severe atopic dermatitis that were inadequately controlled.

RESEARCH AGREEMENT FOR ZIKA VACCINE On July 6, Sanofi announced a Cooperat ive Research and Development Agreement with the Walter Reed Army Institute of Research (WRAIR) on the co-development of a Zika vaccine candidate. WRAIR will transfer its Zika purified inactivated virus vaccine technology to Sanofi Pasteur, opening the door for a broader collaboration with the U.S. government.

In addition to the work on the WRAIR technology, Sanofi Pasteur is performing pre-clinical studies, utilizing a technology previously and successfully developed for both its dengue fever and Japanese encephalitis vaccines. However, since that pathway will take longer to get a Zika vaccine candidate into clinical development, Sanofi Pasteur has also been exploring partnerships with external experts to rapidly advance a vaccine candidate.

A mother and her daughter in Brazil. They had dengue fever within 15 days of each other. In 2015, over 1.4 million Brazilian citizens were reportedly infected with the virus (Secretaria de Vigilância em Saúde − Ministério da Saúde).

Zika, Japanese encephalitis, and dengue belong to the same family of viruses (Flavivirus) and are transmitted by the same type of mosquito.

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6 - SANOFI - LETTER TO SHAREHOLDERS #46 - SEPTEMBER 2016

INDIVIDUAL SHAREHOLDERS COMMITTEE A REGULAR DIALOG BETWEEN SANOFI AND ITS SHAREHOLDERS

The Sanofi individual shareholders committee was created in 2005 to strengthen the dialog and interaction between the company and its shareholders. Currently, the committee has 10 members, selected to reflect the composition of our individual shareholder base in France. The committee meets with the Investor Relations team every quarter to discuss the company’s news, inform Sanofi about individual shareholders’ expectations and participate in the formulation of communication projects.

SHAREHOLDER INFORMATION

To a l low the commit tee to be a rea l l ink between Sanofi and the individual shareholders it represents , the Investor Relations team regularly informs it about the company’s business and invites its members to participate in different communication activities.

In addit ion to quarter ly meetings , the c o m m i t t e e m e m b e r s a r e i nv i t e d t o participate in the annual general meeting and to join the Sanofi team on their stand at the Actionaria shareholder exhibition. Once a year, the committee has the opportunity to visit one of the company’s sites. As a result, the committee members learn more about how a leading pharmaceutical company operates and are able to assess the challenges of an efficient shareholder communication.

SITE VISIT AT NEUVILLE-SUR-SAÔNE

In June 2016, the committee visited the Neuville-sur-Saône site, near Lyon, France, the world’s first and only production facility of the dengue vaccine, Dengvaxia®.

A n t o i n e Q u i n , H e a d o f t h e N e u v i l l e site, presented the ambitious industr ial reconversion of the site that is today the third European production center of Sanofi Pasteur, entirely dedicated to the biotechnological production of Dengvaxia®.

In 2008, six years prior to the publication of Phase III results demonstrating the efficacy of the dengue vaccine, Sanofi decided to invest €300 million in the transformation of the Neuville facility.

The site benefits from the proximity of the Marcy l’Etoile site, the largest vaccines research, development and production c e n t e r w o r l d w i d e a n d t h e g l o b a l headquarters of Sanofi Pasteur in Lyon.

More than 200 employees work in Neuville in different industrial units with key expertise for the manufacturing of Dengvaxia®. These include a vaccine production unit, a unit for the production and distribution of utilities (purified water, compressed air…), another unit for quality control which can also be used for other control activities of different Sanofi Pasteur vaccines; and a building dedicated to the development and improvement of industrial and analytical processes.

The committee visited the Dengvaxia® production unit and had a look at the rooms dedicated to cell and viral culture.

SANOFI - LETTER TO SHAREHOLDERS #46 - SEPTEMBER 2016 - SANOFI - LETTER TO SHAREHOLDERS #46 - SEPTEMBER 2016 - 7

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The committee visited the production unit of Dengvaxia® and was shown the rooms dedicated to cell and viral culture. Thierry Youhanna, head of this unit, explained the different production steps of the active ingredient of Dengvaxia® which respect the highest quality and safety standards.

The committee members were impressed by the complexity of the process, which consists of the production of a very high number of cells that are used to reproduce the live attenuated viruses (four serotypes of the virus are included in the final vaccine). After purification, concentration and filtration the active ingredient (bulk) is ready. Bags containing the bulk are stored at -70°C and transported to another site, Val de Reuil in Upper Normandy, where the final vaccine is produced and packaged.

As the current members of the committee were appointed at the beginning of 2014, the partial reelection of the committee is due at the start of 2017.

Potential candidates should send a letter with an accompanying CV by mail to:

Sanofi Investor Relations54 Rue La Boétie75008 Paris - France

Or by e-mail to: individualshareholders@sanofi.com

Please provide the following information when submitting your application:

• • • •

Your motivations to join the Sanofi committee The number of Sanofi shares you hold, and since which date Your membership in other shareholder committees Your membership in shareholder groups and/or investment clubs

CALL FOR CANDIDATES

PARTIAL REAPPOINTMENT OF THE INDIVIDUAL SHAREHOLDERS COMMITTEE

MEETING WITH THE CFO AND THE NEW CEO

In September 2015, just a few months after the arrival of Olivier Brandicourt as new Chief Executive Officer, the committee met with Olivier Brandicourt and Jérôme Contamine, Chief Financial Officer, on the occasion of a meeting at Sanofi’s headquarters in Paris.

DIALOG WITH THE CHAIRMAN OF THE BOARD

In March 2016, the committee g a t h e r e d a t S a n o f i ’ s headquarters in Paris. During the meeting, the Investor Relations team presented Sanofi’s full-year 2015 results, the strategic roadmap 2020 and discussed communication projects for 2016.

Se rge We inberg , Cha i r man of the Board, joined the group after lunch to talk about the next annual general meeting a n d a n s w e r t h e g r o u p ’ s questions about the company’s perspectives, its dividend policy and new Board members.

❚ COMMITTEE COMPOSITION

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The committee currently counts 10 members (the number can vary between 8 and 12), selected to reflect the composition of our individual shareholder base in France, in terms of their geographical origin, professional background, age, their interest in the healthcare sector and the stock market, and their membership of shareholder associations. No member may belong to more than 3 committees at any time. No current employee of Sanofi may be a member. Members serve for a term of 3 years, renewable at the discretion of Sanofi. The Committee is partially reappointed every 3 years.

❚ ORGANIZATION AND MISSION

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The committee is chaired by our Chief Financial Officer Jérôme Contamine, and organized by the Investor Relations Department. The committee’s language is French. It meets 3 or 4 times a year, generally at the headquarters of Sanofi. One meeting is dedicated to a site visit. The committee also meets every year in November at the Actionaria shareholder exhibition.The committee has two roles: to provide Sanofi with feedback about individual shareholders’ concerns; to work with us on the formulation of our communication projects.

SAVE THE DATE FOR SALON ACTIONARIA 2016

SHARE PERFORMANCE IN PARIS

Forward-looking statement:This letter contains projections and other forward-looking statements that are not historical facts. Although the management of Sanofi believes that these projections and forward-looking statements, and their underlying assumptions, are reasonable as of the date of this letter, investors are cautioned that such projections, assumptions, intentions and forward-looking 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 or implied. These risks and uncertainties include those discussed elsewhere in this letter, as well as in the filings of Sanofi with the U.S. Securities and Exchange Commission (SEC) and the French Autorité des marchés financiers (AMF), notably under the caption “Risk Factors” in the company’s annual report on Form 20-F. Other than as required by applicable law, Sanofi does not undertake any obligation to update any statement that is not a historical fact.

The Letter to Shareholders is published by Sanofi Investor Relations / Shareholder Relations.

Photographs: p. 2: Marthe Lemelle, Denis FELIX - p. 3: Denis FELIX – p. 4: Piotr Redlinski / Capa Pictures - p. 5: Sanofi Pasteur / MarizildaCruppe, Sanofi Pasteur, Peter Strumpf / Capa Pictures – p. 6: Sanofi Pasteur / Vincent Moncorgé, Sanofi Pasteur – p. 7: Franck Parisot – p. 8: Sanofi

Design/production: SEITOSEI

Status: September 13, 2016

SHAREHOLDER INFORMATION

The Sanofi Investor Relations team will be happy to welcome you at the 19th edition of Actionaria, Europe’s largest exhibition for individual shareholders:

On November 18 & 19, 2016Palais des Congrès de Paris2 Place de la Porte Maillot, 75017 Paris

Come and join us at Espace « Grandes Cap », Level 2 - stand E 32, from 9:30 am to 7:00 pm CET on Friday and from 9:30 am to 6:30 pm CET on Saturday.

Our team will be on the stand to discuss the company’s strategy, news and outlook. We will also answer your questions on the Sanofi share price trend, how to hold Sanofi shares and our communication tools for individual shareholders.

You will have access to our publications and the SANOFI IR mobile app on the stand.

CALENDAR

• September 29, 2016: Shareholder meeting in Nice

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October 28, 2016: Third quarter results 2016

November 18-19, 2016: Actionaria exhibition, Paris

November 28, 2016: Shareholder meeting in Tours

SANOFI STOCK

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Euronext Paris, compartment A Member code: SAN ISIN code: FR 0000120578

New York Stock Exchange Symbol: SNY CUSIP number: 80105N105000

SANOFI SHARE PRICE TREND OVER 5 YEARS

Euronext Paris, from January 1, 2011 to August 29, 2016

CAC 40 rebased on the Sanofi share. Source: vwdgroup

100

90

80

70

60

50

40

30

Jan 11 Jan 12 Jan 16Jan 14Jan 13 Jan 15 August 29,2016

SANOFI E69.43+45.1%

CAC 40 4,424.25 points

+16.3%

Request a free invitation:

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• Sending an e-mail to: individualshareholders@sanofi.com

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By calling: +33 (0) 800 075 876

Or visiting the Actionaria Website at: www.actionaria.com

SHAREHOLDER RELATIONS

@

SANOFI - Shareholder Relations 54, rue La Boétie - 75 008 Paris - France

Tel. Europe: +33 (0) 800 075 876Toll-free tel. U.S.: +1 888 516 3002

Individualshareholders@sanofi.com

www.sanofi.com/shareholders

Mobile app: SANOFI IR (available in the App Store and Google Play)