UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Amendment No.    )

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Nektar Therapeutics

(Name of Registrant as Specified In Its Charter)

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

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*** Exercise Your Right to Vote ***

Important Notice Regarding the Availability of Proxy Materials for the

Stockholder Meeting to Be Held on June 13, 2013.

NEKTAR THERAPEUTICS

NEKTARTM

NEKTAR THERAPEUTICS

ATTN: GIL LABRUCHERIE

455 MISSION BAY BOULEVARD SOUTH

SAN FRANCISCO, CA 94158

Meeting Information

Meeting Type: Annual Meeting

For holders as of: April 15, 2013

Date: June 13, 2013 Time: 2:00 PM Pacific Time

Location:

Nektar Therapeutics

455 Mission Bay Blvd. South

San Francisco, CA 94158

You are receiving this communication because you hold shares in the company named above.

This is not a ballot. You cannot use this notice to vote these shares. This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. You may view the proxy materials online at www.proxyvote.com or easily request a paper copy (see reverse side).

We encourage you to access and review all of the important information contained in the proxy materials before voting.

See the reverse side of this notice to obtain proxy materials and voting instructions.

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– Before You Vote –

How to Access the Proxy Materials

Proxy Materials Available to VIEW or RECEIVE:

NOTICE AND PROXY STATEMENT ANNUAL REPORT

How to View Online:

Have the information that is printed in the box marked by the arrow XXXX XXXX XXXX (located on the following page) and visit: www.proxyvote.com.

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If you want to receive a paper or e-mail copy of these documents, you must request one. There is NO charge for requesting a copy. Please choose one of the following methods to make your request:

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3) BY E-MAIL*: sendmaterial@proxyvote.com

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– How To Vote –

Please Choose One of the Following Voting Methods

Vote In Person: Many stockholder meetings have attendance requirements including, but not limited to, the possession of an attendance ticket issued by the entity holding the meeting. Please check the meeting materials for any special requirements for meeting attendance. At the meeting, you will need to request a ballot to vote these shares.

Vote By Internet: To vote now by Internet, go to www.proxyvote.com. Have the information that is printed in the box marked by the arrow XXXX XXXX XXXX (located on the following page) available and follow the instructions.

Vote By Mail: You can vote by mail by requesting a paper copy of the materials, which will include a proxy card.

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Voting Items

The Board of Directors recommends a vote “FOR” each nominee listed in Proposal 1 and “FOR” Proposals 2 and 3.

1. To elect three directors with terms to expire at the 2016 Annual Meeting of Stockholders;

Nominees:

1a. R. Scott Greer

1b. Christopher A. Kuebler

1c. Lutz Lingnau

2. To ratify the selection of Ernst & Young LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2013.

3. To approve a non-binding advisory resolution regarding our executive compensation (a “say-on-pay” vote).

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