Goldman, Sachs & Co.

Exhibit 10.86

Xxxxxxx, Xxxxx & Co.

000 Xxxx Xxxxxx

Xxx Xxxx, Xxx Xxxx 00000-0000

Telephone No.:    (000) 000-0000

August 30, 2010

To: Gilead Sciences, Inc.

000 Xxxxxxxx Xxxxx

Xxxxxx Xxxx, Xxxxxxxxxx 00000

Attention:		Treasurer
Telephone No.:		(000) 000-0000
Facsimile No.:		(000) 000-0000

Re: Base Call Option Transaction (2014)

Reference is made to the letter agreement Re: Base Call Option Transaction (2014) dated July 26, 2010 and entered into between into between Xxxxxxx, Sachs & Co. (“Dealer”) and Gilead Sciences, Inc. (“Counterparty”) (the “Confirmation”). Capitalized terms used herein but not defined herein shall have the meanings assigned to them in the Confirmation.

Whereas the Confirmation defined the Free Convertibility Date as April 1, 2014, but Counterparty and Dealer wish to define the Free Convertibility Date as February 1, 2014;

Now therefore, Counterparty and Dealer do hereby agree that the definition of the Free Convertibility Date in the Confirmation is hereby replaced in its entirety by February 1, 2014.

[Signature Page to Follow]

Yours faithfully,
Xxxxxxx, Xxxxx & Co.
By:		/s/ Xxxxxxxx Xxxxxxx
Name:		Xxxxxxxx Xxxxxxx
Title:		Vice President

Accepted and confirmed:

Gilead Sciences, Inc.
By:		/s/ Xxxxx X. Xxxxxxxx
Name:		Xxxxx X. Xxxxxxxx
Title:		Vice President and General Counsel