<PAGE>
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
---------------------------------
AMENDMENT NO. 5 TO
SCHEDULE TO
(Rule 14d-100)
TENDER OFFER STATEMENT PURSUANT TO SECTION 14(d)(1)
OF THE SECURITIES EXCHANGE ACT OF 1934
Acuson Corporation
(Name of Subject Company (Issuer))
Sigma Acquisition Corp.
a wholly-owned subsidiary of
Siemens Corporation
an indirect wholly-owned subsidiary of
Siemens Aktiengesellschaft
(Names of Filing Persons (Offerors))
Common Stock, $0.0001 par value
(Title of Class of Securities)
005113105
(CUSIP Number of class of securities)
Kevin M. Royer
Siemens Corporation
153 East 53rd Street
New York, New York 10022
(212) 258-4000
(Name, Address and Telephone No. of Person Authorized to Receive
Notices and Communications on Behalf of Filing Persons)
with a copy to:
John A. Healy, Esq.
Clifford Chance Rogers & Wells LLP
200 Park Avenue,
New York, New York 10166
(212) 878-8000
---------------------------------
Calculation of Filing Fee
--------------------------------------------------------------------------------
Transaction Valuation Amount of Filing Fee
$812,694,742 $162,539*
--------------------------------------------------------------------------------
*Previously paid.
[_] Check the box if the filing relates solely to preliminary
communications made before 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: [_]
<PAGE>
AMENDMENT NO. 5 TO SCHEDULE TO
This Amendment No. 5 amends and supplements the Tender Offer Statement on
Schedule TO, originally filed with the Securities and Exchange Commission (the
"Commission") on October 5, 2000, as amended by Amendment No. 1 filed with the
Commission on October 12, 2000, Amendment No. 2 filed with the Commission on
October 13, 2000, Amendment No. 3 filed with the Commission on October 19, 2000
and Amendment No. 4 filed with the Commission on October 20, 2000 (the "Schedule
TO"), relating to the offer by Sigma Acquisition Corp., a Delaware corporation
("Purchaser"), which is a wholly-owned subsidiary of Siemens Corporation, a
Delaware corporation ("Parent"), which is an indirect wholly-owned subsidiary of
Siemens Aktiengesellschaft, a corporation formed under the laws of the Federal
Republic of Germany ("Siemens AG"), to purchase all of the outstanding shares of
common stock, par value $0.0001 per share ("Common Stock"), of Acuson
Corporation, a Delaware corporation (the "Company"), together with the
associated rights to purchase shares of series A preferred stock ("Rights")
issued pursuant to the Amended and Restated Rights Agreement, dated as of
November 5, 1998, between the Company and Fleet National Bank (f/k/a BankBoston,
N.A.), as amended (the Common Stock and the Rights together being referred to
herein as the "Shares"), at a price of $23.00 per Share, net to the seller in
cash, upon the terms and subject to the conditions set forth in the Offer to
Purchase, dated October 5, 2000 (the "Offer to Purchase"), a copy of which was
attached as Exhibit (a)(1) to the Schedule TO, and in the related Letter of
Transmittal, a copy of which was attached to the Schedule TO as Exhibit (a)(2).
Schedule TO
The Schedule TO is hereby supplemented and/or amended as provided below.
Item 11. Additional Information.
Item 11 of the Schedule TO is amended by adding the following:
The applicable waiting period under the U.S. Hart-Scott-Rodino
Antitrust Improvements Act of 1976, as amended, was terminated on November
2, 2000.
For additional information regarding the expiration of the waiting
period, see the text of the press release filed as an exhibit hereto.
Item 12. Exhibits.
Item 12 of the Schedule TO is amended by adding the following:
(a)(10) Press release issued by Siemens, dated November 2, 2000,
announcing the termination of the waiting period under the
HSR Act.
- 2 -
<PAGE>
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.
Date: November 2, 2000 SIGMA ACQUISITION CORP.
/s/ Michael W. Schiefen
------------------------------------------
Name: Michael W. Schiefen
Title: President
/s/ E. Robert Lupone
------------------------------------------
Name: E. Robert Lupone
Title: Vice President
SIEMENS CORPORATION
/s/ Michael W. Schiefen
------------------------------------------
Name: Michael W. Schiefen
Title: Vice President-Corporate Development
/s/ E. Robert Lupone
------------------------------------------
Name: E. Robert Lupone
Title: Senior Vice President, General Counsel and
Secretary
SIEMENS AKTIENGESELLSCHAFT
/s/ Erich Reinhardt
------------------------------------------
Name: Erich Reinhardt
Title: Chief Executive Officer and Group
President, Medical Engineering
Division of Siemens
/s/ Goetz Steinhardt
------------------------------------------
Name: Goetz Steinhardt
Title: Corporate Vice President, Medical
Engineering Division of Siemens
- 3 -