SC TO-T/A

QuickLinks -- Click here to rapidly navigate through this document

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, DC 20549

SCHEDULE TO/A
TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1)
OF THE SECURITIES EXCHANGE ACT OF 1934
(Amendment No. 6)

ADVANCED NEUROMODULATION SYSTEMS, INC.
(Name of Subject Company (Issuer))

APOLLO MERGER CORP.
a wholly-owned subsidiary of
ST. JUDE MEDICAL, INC.
(Name of Filing Persons (Offerors))

COMMON STOCK, $0.05 PAR VALUE PER SHARE
(Title of Class of Securities)

00757T101
(CUSIP Number of Class of Securities)

KEVIN T. O'MALLEY
ST. JUDE MEDICAL, INC.
GENERAL COUNSEL
ONE LILLEHEI PLAZA
ST. PAUL, MINNESOTA 55117
(651) 483-2000
(Name, address, and telephone number of person
authorized to receive notices and communications on behalf of filing persons)

With Copies to:
JOSEPH BARBEAU
GIBSON, DUNN & CRUTCHER LLP
1881 PAGE MILL ROAD
PALO ALTO, CALIFORNIA 94304-1125
(213) 229-7000
and
JAMES J. MOLONEY
GIBSON, DUNN & CRUTCHER LLP
4 PARK PLAZA
IRVINE, CALIFORNIA 92614-8557
(949) 451-3800

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

ý  third party tender offer subject to Rule 14d-l

o  issuer tender offer subject to Rule 13e-4

o  going-private transaction subject to Rule 13e-3

o  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. ý

Amendment No. 6 to Schedule TO

        This Amendment No. 6 (this "Amendment") further amends and supplements the Tender Offer Statement on Schedule TO filed with the Securities and Exchange Commission on October 18, 2005, as amended on October 19, 2005, November 4, 2005, November 14, 2005, November 16, 2005 and November 21, 2005 (the "Schedule TO"), relating to the third-party tender offer by Apollo Merger Corp., a Texas corporation (the "Purchaser") and a wholly-owned subsidiary of St. Jude Medical, Inc., a Minnesota corporation ("Parent"), to purchase all of the issued and outstanding shares of common stock of Advanced Neuromodulation Systems, Inc., a Texas corporation (the "Company"), par value $0.05 per share (together with the associated rights issued pursuant to the Rights Agreement dated August 30, 1996 between Quest Medical, Inc. and KeyCorp Shareholder Services, Inc., as rights agent, as amended by the Amendment to Rights Agreement dated January 25, 2002 between the Company and Computershare Investor Services LLC and Amendment No. 2 to Rights Agreement dated October 14, 2005 between the Company and Computershare Investor Services LLC (as so amended, the "Rights Plan")) (the "Shares"), at a purchase price of $61.25 per share, net to the seller in cash, without interest thereon, upon the terms and subject to the conditions set forth in the Offer to Purchase, dated October 18, 2005 (the "Offer to Purchase") and in the related Letter of Transmittal (the "Letter of Transmittal"), copies of which were filed as Exhibits (a)(1)(A) and (a)(1)(B) to the Schedule TO (which, together with any amendments or supplements thereto, collectively constitute the "Offer"). This Amendment is being filed on behalf of Purchaser and Parent and is the final amendment to the Schedule TO. Capitalized terms used and not defined in this Amendment have the meanings specified in the Offer to Purchase or the Schedule TO.

Item 12.    Exhibits

(a)(5)(H)    Press Release issued by Parent on November 28, 2005.

1

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.

	Apollo Merger Corp.
	By:	/s/  KEVIN T. O'MALLEY Name: Kevin T. O'Malley Title: Vice President and Secretary
	St. Jude Medical, Inc.
	By:	/s/  KEVIN T. O'MALLEY Name: Kevin T. O'Malley Title: Vice President and General Counsel
Dated: November 28, 2005

2

EXHIBIT INDEX

Exhibit Number	Description
(a)(1)(A)	Offer to Purchase, dated October 18, 2005.*
(a)(1)(B)	Form of Letter of Transmittal.*
(a)(1)(C)	Form of Notice of Guaranteed Delivery.*
(a)(1)(D)	Form of Letter to Brokers, Dealers, Commercial Banks, Trust Companies and other Nominees.*
(a)(1)(E)	Form of Letter to Clients for use by Brokers, Dealers, Commercial Banks, Trust Companies and other Nominees.*
(a)(1)(F)	Summary Advertisement as published in The Wall Street Journal on October 18, 2005.*
(a)(1)(G)	Transcript of Earnings Release Conference Call on October 17, 2005.*
(a)(5)(A)	Joint Press Release issued on October 16, 2005 (incorporated by reference from Exhibit 99.1 of the Parent's Current Report on Form 8-K filed on October 17, 2005).*
(a)(5)(B)	Press Release issued by Parent on October 17, 2005 (incorporated by reference from Exhibit 99.1 of the Parent's Current Report on Form 8-K filed on October 17, 2005).*
(a)(5)(C)	Press Release issued by Parent on October 18, 2005.*
(a)(5)(D)	Press Release issued by Parent on November 4, 2005.*
(a)(5)(E)	Press Release issued by Parent on November 11, 2005.*
(a)(5)(F)	Press Release issued by Parent on November 16, 2005.*
(a)(5)(G)	Press Release issued by Parent on November 21, 2005.*
(a)(5)(H)	Press Release issued by Parent on November 28, 2005.†
(d)(1)	Agreement and Plan of Merger, dated as of October 15, 2005, by and among St. Jude Medical, Inc., Apollo Merger Corp. and Advanced Neuromodulation Systems, Inc.*
(d)(2)	Confidentiality Agreement, dated as of July 28, 2005, by and between Advanced Neuromodulation Systems, Inc. and St. Jude Medical, Inc.*

*

Previously filed.

†

Filed herewith.

3

QuickLinks

Amendment No. 6 to Schedule TO
Signature
EXHIBIT INDEX

EX-99.(A)(5)(H)

Exhibit (a)(5)(H)

ST. JUDE MEDICAL
News Release...

			St. Jude Medical One Lillehei Plaza St. Paul, Minnesota 55117 (651) 483.2000 www.sjm.com
Contacts	Laura Merriam Investor Relations (651) 766-3029	Angela Craig Media Relations (651) 481-7789

St. Jude Medical Completes Tender Offer for Advanced Neuromodulation Systems

Advanced Neuromodulation Systems Shareholders Tender
More Than 90 Percent of Outstanding Shares

ST. PAUL, MN, November 28, 2005—St. Jude Medical, Inc. (NYSE:STJ) announced today the successful completion of its cash tender offer for all of the outstanding shares of Advanced Neuromodulation Systems, Inc. (NASDAQ:ANSI).

The subsequent offering period of St. Jude Medical's tender offer to purchase all of the outstanding shares of ANS expired at 5:00 p.m., Eastern Time, on Monday, November 28, 2005. Including those shares tendered during the initial offering period, ANS shareholders have now tendered 18,383,596 shares, or more than 90 percent of the outstanding shares of ANS, and promised to deliver 619,237 additional shares, or approximately 3 percent of the outstanding shares of ANS, under notices of guaranteed delivery. St. Jude Medical has accepted for purchase and payment all of the ANS shares that were validly tendered and not properly withdrawn in the offer.

St. Jude Medical expects to acquire the remaining shares of ANS (those not delivered during the offer or pursuant to notices of guaranteed delivery) through a "short-form" merger between its wholly-owned subsidiary and ANS on Tuesday, November 29, 2005. In the merger, each outstanding share of ANS common stock will be converted into the right to receive $61.25 in cash per share, without interest, the same consideration paid for shares tendered in the offer, subject to dissenters' rights. A letter of transmittal to be used for surrendering share certificates in exchange for payment will be sent to shareholders who did not tender their shares in the offer. Following the merger, ANS will be a wholly-owned subsidiary of St. Jude Medical.

MacKenzie Partners, Inc. is acting as information agent in connection with the tender offer and can be contacted at (800) 322-2885 (toll free) or (212) 929-5500 (collect). The Dealer Manager for the tender offer is Banc of America Securities LLC.

About St. Jude Medical
St. Jude Medical, Inc. (www.sjm.com) is dedicated to the design, manufacture and distribution of innovative medical devices of the highest quality, offering physicians, patients and payers outstanding clinical performance and demonstrated economic value.

About ANS
ANS (www.ANS-medical.com) designs, develops, manufacturers and markets implantable systems used to manage chronic intractable pain and other disorders of the central nervous system.

Forward-Looking Statements
Any statements made regarding the proposed transaction between St. Jude Medical, Inc. and Advanced Neuromodulation Systems, Inc., the expected timetable for completing the transaction, successful integration of the business, benefits of the transaction, potential clinical success, regulatory approvals, anticipated future product launches, revenues, earnings, expected repayment of debt, market shares, market growth, market segment growth, new indications, and any other statements regarding St. Jude Medical's or ANS's future expectations, beliefs, goals or prospects are forward-looking statements which are subject to risks and uncertainties, such as those described under or incorporated by reference in the Cautionary Statements section in Item 2 of St. Jude Medical's Quarterly Report on Form 10-Q filed on November 8, 2005 (see page 35), and in Item 8.01 of ANS's Current Report on Form 8-K filed on October 17, 2005, and in the Outlook and Uncertainties section in ANS's Quarterly Report on Form 10-Q for the quarter ended September 30, 2005 (see page 26), and ANS's Annual Report on Form 10-K for the year ended December 31, 2004 (see page 26). Actual results may differ materially from anticipated results.