SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a)

of the Securities Exchange Act of 1934 (Amendment No.)

Filed by the Registrant    o

Filed by a Party other than the Registrant    x

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o Preliminary Proxy Statement

o Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

o Definitive Proxy Statement

x Definitive Additional Materials

o Soliciting Material Pursuant to § 240.14a-12

GENZYME CORPORATION

(Name of Registrant as Specified In Its Charter)

DR. STEVEN BURAKOFF

DR. ALEXANDER J. DENNER

MR. CARL C. ICAHN

DR. RICHARD MULLIGAN

DR. ERIC ENDE

HIGH RIVER LIMITED PARTNERSHIP

HOPPER INVESTMENTS LLC

BARBERRY CORP.

ICAHN PARTNERS LP

ICAHN PARTNERS MASTER FUND LP

ICAHN PARTNERS MASTER FUND II LP

ICAHN PARTNERS MASTER FUND III LP

ICAHN ENTERPRISES G.P. INC.

ICAHN ENTERPRISES HOLDINGS L.P.

IPH GP LLC

ICAHN CAPITAL L.P.

ICAHN ONSHORE LP

ICAHN OFFSHORE LP

BECKTON CORP.

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

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Report of Economists Incorporated Regarding 2009 Clayton Act Thresholds for Competing Sales of Rituxan and Campath

Proskauer Rose LLP, antitrust counsel to the Icahn Parties, engaged Economists Incorporated to undertake economic analyses related to the application of certain de minimus provisions of Section 8 of the Clayton Act (Section 8) to potential board of director overlaps between Genzyme Corporation (“Genzyme”) and Biogen Idec Inc. (“Biogen”).  On June 3, 2010 Economists Incorporated delivered a report  (“Report”) to Proskauer Rose LLP which states the following conclusion (qualified in its entirety by the Report, a copy of which is attached hereto as Exhibit 1 and which we strongly suggest be read in its entirety).

“Conclusion

Using worldwide sales data, Section 8’s 2% de minimus test is met for both Genzyme and Biogen (See Figures 1-3, 5). With respect to Genzyme, its worldwide gross sales revenues from the sale of Campath relative to its total worldwide gross sales revenues are below 2%. Similarly, with respect to Biogen, Biogen’s worldwide gross revenues from the sale of off-label Rituxan are less than 2% of Biogen’s total worldwide gross revenues.

As is shown in Figure 4 and Figure 6, Section 8 shares below 2% are also found if one calculates these ratios for the United States, rather than the world.

Given that both Genzyme’s and Biogen’s Section 8 competitive sales ratios are below 2%, the ratios are below both the one-firm 2% de minimus benchmark and the two-firm 4% de minimus benchmark.”1

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All shareholders of Genzyme are advised to read the definitive proxy statement and the gold proxy card filed with the SEC on May 4, 2010 and other documents related to the solicitation of proxies by the Participants from the shareholders of Genzyme for use at the 2010 annual meeting of shareholders of Genzyme because they contain important information. The definitive proxy statement and form of proxy along with other relevant documents are available at no charge on the SEC’s website at http://www.sec.gov or by contacting D.F. King & Co., Inc. by telephone toll free at (800) 347-4750 or by visiting their website www.dfking.com/genzyme.  In addition, the Participants will provide copies of the definitive proxy statement without charge upon request.

 

1 Genzyme has not put forth factual evidence to support a violation of the Clayton Act. Genzyme has stated in its soliciting materials that “[n]either the FTC nor any other judicial or regulatory authority charged with the administration and/or interpretation of the Clayton Act has made a factual determination that the election of Dr. Denner of Dr. Mulligan would violate the Clayton Act. “ Although the Icahn Parties believe that the election of Drs. Denner and Mulligan to the Board of Genzyme would not constitute a violation of the Clayton Act, the Icahn Parties are unable to confirm that a violation of the Clayton Act would not occur if Drs. Denner and Mulligan were elected to the Board, even absent a final determination by the relevant regulatory authorities and/or courts.