SC TO-T/A

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE TO

Tender Offer Statement under Section 14(d)(1) or 13(e)(1)

of the Securities Exchange Act of 1934

(Amendment No. 6)

Pharmasset, Inc.

(Name of Subject Company (Issuer))

Gilead Sciences, Inc.

Royal Merger Sub Inc.

Royal Merger Sub II Inc.

(Names of Filing Persons (Offerors))

Common Stock, par value $0.001 per share

(Title of Class of Securities)

71715N106

(CUSIP Number of Class of Securities)

Brett A. Pletcher, Esq.

Senior Vice President and General Counsel

Gilead Sciences, Inc.

333 Lakeside Drive

Foster City, California 94404

Tel: (650) 574-3000

(Name, Address and Telephone Numbers of Person Authorized to Receive Notices and Communications on Behalf of Filing Persons)

Copy to:

Franklin M. Gittes, Esq.

Stephen F. Arcano, Esq.

Brandon Van Dyke, Esq.

Skadden, Arps, Slate, Meagher & Flom LLP

4 Times Square

New York, New York 10036

(212) 735-3000

CALCULATION OF FILING FEE

Transaction Valuation(1)	Amount of Filing Fee(2)
$11,177,775,885	$1,280,973

(1) Estimated solely for purposes of calculating the filing fee. The transaction value was determined by multiplying (x) $137 (i.e., the tender offer price) and (y) 81,589,605, the estimated maximum number of shares of Pharmasset common stock to be acquired in the tender offer.

(2) The filing fee was calculated in accordance with Rule 0-11 under the Securities Exchange Act of 1934, as amended, and Fee Rate Advisory #3 for Fiscal Year 2012, issued September 29, 2011, by multiplying the transaction value by 0.0001146.

x Check the box if any part of the fee is offset as provided by Rule 0-11 (a)(2) and identify the filing with which the offsetting fee was previously paid. Identify the previous filing by registration statement number, or the Form or Schedule and the date of its filing.

Amount Previously Paid:	$1,280,973	Filing Party:	Gilead Sciences, Inc.
Form or Registration No.:	Schedule TO	Date Filed:	December 6, 2011

¨ Check the box if the filing relates solely to preliminary communications made before the commencement of a tender offer.

Check the appropriate boxes below to designate any transactions to which the statement relates:

x third-party tender offer subject to Rule 14d-1.

¨ issuer tender offer subject to Rule 13e-4.

¨ going-private transaction subject to Rule 13e-3.

¨ amendment to Schedule 13D under Rule 13d-2.

Check the following box if the filing is a final amendment reporting the results of the tender offer:    x

This Amendment No. 6 amends and supplements the Tender Offer Statement on Schedule TO (as amended, “Schedule TO”) relating to the offer by Gilead Sciences, Inc., a Delaware corporation (“Gilead”), Royal Merger Sub Inc., a Delaware corporation and direct wholly-owned subsidiary of Gilead (“Merger Sub”), and Royal Merger Sub II Inc., a Delaware corporation and indirect wholly-owned subsidiary of Gilead (“Merger Sub II” and, together with Gilead and Merger Sub, the “Offerors”), to purchase all outstanding shares of common stock, par value $0.001 (“Shares”), of Pharmasset, Inc., a Delaware corporation (“Pharmasset”), at a price of $137 per Share, net to the seller in cash (less any required withholding taxes and without interest) (the “Offer Price”), upon the terms and subject to the conditions set forth in the Offer to Purchase dated December 6, 2011 (together with any amendments or supplements thereto, the “Offer to Purchase”) and in the related Letter of Transmittal (together with any amendments or supplements thereto, the “Letter of Transmittal” and, together with the Offer to Purchase, the “Offer”), which are annexed to and filed with this Schedule TO as Exhibits (a)(1)(A) and (a)(1)(B), respectively.

All the information set forth in the Offer to Purchase, to the extent incorporated by reference therein, is hereby amended and supplemented as set forth below.

Item 11.   ADDITIONAL INFORMATION

Item 11 of the Schedule TO is hereby amended and supplemented by adding the following text thereto:

“On January 17, 2012, Purchaser merged with and into Pharmasset, with Pharmasset continuing as the surviving corporation. In order to accomplish the Merger as a “short-form” merger, Purchaser exercised its “top-up” option pursuant to the Merger Agreement, which permitted Purchaser to purchase additional Shares directly from Pharmasset for $137 per Share (the same purchase price paid in the Offer). All outstanding Shares, other than (i) Shares owned by Gilead, Purchaser or any of their direct or indirect wholly-owned subsidiaries, (ii) Shares owned by Pharmasset or its subsidiary and (iii) Shares held by Pharmasset stockholders who properly demand appraisal for their Shares under Delaware law, were canceled and converted into the right to receive cash equal to the $137 price per Share.

Shares ceased trading on the NASDAQ Global Select Market at the close of market on January 17, 2012.”

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ITEM 12. EXHIBITS.

Item 12 of the Schedule TO is hereby amended and supplemented to add the following exhibit:

(a)(1)(J) Press Release of Gilead dated January 17, 2012.

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SIGNATURE

After due inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated: January 17, 2012

GILEAD SCIENCES, INC.
By:	/s/ BRETT A. PLETCHER
Name:	Brett A. Pletcher
Title:	Senior Vice President and General Counsel
ROYAL MERGER SUB INC.
By:	/s/ BRETT A. PLETCHER
Name:	Brett A. Pletcher
Title:	Secretary
ROYAL MERGER SUB II INC.
By:	/s/ BRETT A. PLETCHER
Name:	Brett A. Pletcher
Title:	Secretary

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EXHIBIT INDEX

(a)(1)(A)	Offer to Purchase, dated December 6, 2011*
(a)(1)(B)	Letter of Transmittal*
(a)(1)(C)	Notice of Guaranteed Delivery*
(a)(1)(D)	Letter to Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees*
(a)(1)(E)	Letter to Clients for Use by Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees*
(a)(1)(F)	Internal Revenue Service Form W-9 (Request for Taxpayer Identification Number and Certification), including instructions for completing the form*
(a)(1)(G)	Joint Press Release of Gilead and Pharmasset dated November 21, 2011 (incorporated by reference to Exhibit 99.1 to the Current Report on Form 8-K filed by Gilead with the Securities and Exchange Commission on November 21, 2011)*
(a)(1)(H)	Investor Presentation Slides (incorporated by reference to Exhibit 99.2 to the Current Report on Form 8-K filed by Gilead with the Securities and Exchange Commission on November 21, 2011)*
(a)(1)(I)	Summary Advertisement, published December 6, 2011 in The Wall Street Journal*
(a)(1)(J)	Press Release of Gilead dated January 6, 2012*
(a)(1)(K)	Press Release of Gilead dated January 12, 2012*
(a)(1)(J)	Press Release of Gilead dated January 17, 2012
(a)(2)	Not applicable
(a)(3)	Not applicable
(a)(4)	Not applicable
(b)	Not applicable
(d)(1)	Agreement and Plan of Merger, dated as of November 21, 2011, among Gilead, Merger Sub and Pharmasset (incorporated by reference to Exhibit 2.1 to the Current Report on Form 8-K filed by Gilead with the Securities and Exchange Commission on November 25, 2011)*
(g)	Not applicable
(h)	Not applicable

* Previously filed

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EX-99.(A)(1)(J)

Exhibit (a)(1)(J)

CONTACTS:	Susan Hubbard, Investors
	(650) 522-5715
	Amy Flood, Media
	(650) 522-5643

For Immediate Release

GILEAD SCIENCES COMPLETES ACQUISITION OF PHARMASSET, INC.

Foster City, California, January 17, 2012 — Gilead Sciences, Inc. (Nasdaq: GILD) today announced the completion of the previously announced transaction for Royal Merger Sub II Inc., a wholly-owned subsidiary of Gilead (“Merger Sub II”), to acquire Pharmasset, Inc. (Nasdaq: VRUS) for $137 per share in cash, or approximately $11.2 billion in the aggregate.

On November 21, 2011, Gilead and Pharmasset announced that Pharmasset, Gilead and Royal Merger Sub Inc., a wholly-owned subsidiary of Gilead (“Merger Sub”), had signed a definitive merger agreement pursuant to which a tender offer would be made. Pursuant to the merger agreement, Gilead, Merger Sub and Merger Sub II commenced a tender offer on December 6, 2011 to acquire all outstanding shares of Pharmasset at a price of $137 per share, net to the seller in cash (less any required withholding taxes and without interest). On January 12, 2012, Gilead announced that it had successfully completed the tender offer for all outstanding shares of common stock of Pharmasset and had accepted for payment all shares validly tendered and not withdrawn as of the expiration time of the tender offer and would promptly pay for such shares, which shares represented approximately 95% of Pharmasset’s outstanding shares (including 5,529,352 shares delivered through Notices of Guaranteed Delivery, representing approximately 7% of the shares outstanding). The rights of Merger Sub under the merger agreement were assigned to Merger Sub II on January 12, 2012. Pursuant to the terms of the merger agreement, Merger Sub II merged with and into Pharmasset on January 17, 2012. In order to accomplish the merger as a “short-form” merger, Merger Sub II exercised its “top-up” option pursuant to the merger agreement, which permitted Merger Sub II to purchase additional shares of common stock of Pharmasset directly from Pharmasset for $137 per share (the same purchase price paid in the offer). All outstanding shares of common stock of Pharmasset, other than (i) shares owned by Gilead, Merger Sub II or any of their direct or indirect wholly-owned subsidiaries, (ii) shares owned by Pharmasset or its subsidiary and (iii) shares held by Pharmasset stockholders who properly demand appraisal for their shares under Delaware law, were canceled and converted into the right to receive cash equal to the $137 price per share.

As a result of the completion of the merger, Pharmasset has become a wholly-owned subsidiary of Gilead and the common stock of Pharmasset will no longer be listed for trading on the NASDAQ Global Select Market, which is expected to take effect as of the close of market on January 17, 2012.

Barclays Capital, Inc. and Bank of America Merrill Lynch acted as financial advisors to Gilead. Skadden, Arps, Slate, Meagher & Flom LLP acted as Gilead’s legal advisors.

Morgan Stanley & Co. LLC acted as financial advisors to Pharmasset. Sullivan & Cromwell LLP acted as Pharmasset’s legal advisors.

About Pharmasset

Pharmasset is a clinical-stage pharmaceutical company committed to discovering, developing and commercializing novel drugs to treat viral infections. Pharmasset’s primary focus is the development of oral therapeutics for the treatment of hepatitis C virus (HCV) infection. Pharmasset’s research and development efforts are focused on nucleoside/tide analogs, a class of compounds which act as alternative substrates for the viral polymerase, thus inhibiting viral replication.

About Gilead Sciences

Gilead Sciences is a biopharmaceutical company that discovers, develops and commercializes innovative therapeutics in areas of unmet medical need. Gilead’s mission is to advance the care of patients suffering from life-threatening diseases worldwide. Headquartered in Foster City, California, Gilead has operations in North America, Europe and Asia Pacific.

Forward-Looking Statements

This press release includes forward-looking statements, within the meaning of the Private Securities Litigation Reform Act of 1995, that are subject to risks, uncertainties and other factors. All statements other than statements of historical fact are statements that could be deemed forward-looking statements, including all statements regarding the intent, belief or current expectation of Gilead. Forward-looking statements include, without limitation, statements regarding business combination and similar transactions, prospective performance and opportunities and the outlook for the companies’ businesses, including, without limitation, the ability of Gilead to advance Pharmasset’s product pipeline or develop an all-oral antiviral regimen for HCV, performance and opportunities and regulatory approvals, the anticipated timing of data from clinical data; the possibility of unfavorable results of the companies’ clinical trials; and any assumptions underlying any of the foregoing. Investors are cautioned that any such forward-looking statements are not guarantees of future performance and involve risks and uncertainties and are cautioned not to place undue reliance on these forward-looking statements. Actual results may differ materially from those currently anticipated due to a number of risks and uncertainties. Risks and uncertainties that could cause the actual results to differ from expectations contemplated by forward-looking statements include: the effects of the transaction on relationships with employees, customers, other business partners or governmental entities; other business effects, including the effects of industry, economic or political conditions outside of the companies’ control; transaction costs; actual or contingent liabilities; and other risks and uncertainties detailed from time to time in Gilead’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2011, as filed with the U.S. Securities and Exchange Commission. All forward-looking statements are based on information currently available to Gilead, and Gilead assumes no obligation to update any such forward-looking statements.

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