FORM 424B7

Filed Pursuant to Rule 424(b)(3) and 424(b)(7)

File No. 333-131373

PROSPECTUS SUPPLEMENT NO. 6

(To Prospectus dated January 30, 2006, as supplemented

by Prospectus Supplement No. 1 dated May 16, 2006, by Prospectus Supplement No. 2 dated May 19, 2006, by Prospectus Supplement No. 3 dated May 26, 2006, by Prospectus Supplement No. 4 dated June 2, 2006 and by Prospectus Supplement No. 5 dated June 9, 2006)

13,525,195 Shares

LOGO

Common Stock

 


The following information supplements information contained in the prospectus dated January 30, 2006, as supplemented by prospectus supplement No. 1 dated May 16, 2006, by prospectus supplement No. 2 dated May 19, 2006, by prospectus supplement No. 3 dated May 26, 2006, by prospectus supplement No. 4 dated June 2, 2006 and by prospectus supplement No. 5 dated June 9, 2006 (together, the “Prospectus”), relating to the resale by selling stockholders, including their respective transferors, donees, pledgees or successors in interest, of our common stock issued or issuable upon the exercise of warrants that were sold to those investors identified in this prospectus supplement in 2000 and 2001 private placements of our common stock and warrants to purchase our common stock. This prospectus supplement should be read in conjunction with the Prospectus, and is qualified by reference to the Prospectus, except to the extent that the information presented herein supersedes the information contained in the Prospectus. This prospectus supplement is not complete without, and may not be delivered or utilized except in connection with, the Prospectus, including any amendments or supplements thereto.

The shares of our common stock are quoted on The Nasdaq National Market under the symbol “NDAQ.”

Investing in our common stock involves risks that are described in the “Risk Factors” section of our Annual Report on Form 10-K and our Quarterly Reports on Form 10-Q that are incorporated by reference in this prospectus supplement.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement is truthful or complete. Any representation to the contrary is a criminal offense.

 


The date of this prospectus supplement is June 16, 2006.


SELLING STOCKHOLDERS

The following table supplements the table of selling stockholders and related footnotes appearing under the heading “Selling Stockholders” of the prospectus dated January 30, 2006, as supplemented by prospectus supplement No. 1 dated May 16, 2006, by prospectus supplement No. 2 dated May 19, 2006, by prospectus supplement No. 3 dated May 26, 2006, by prospectus supplement No. 4 dated June 2, 2006 and by prospectus supplement No. 5 dated June 9, 2006 by adding or supplementing the information below with respect to selling stockholders. When we refer to the “selling stockholders” in this prospectus supplement, we mean those persons listed in the table below, as well as the pledgees, donees, assignees, transferees, successors and others who hold any of the selling stockholders’ interest. The shares of our common stock offered by this prospectus supplement include the shares of our common stock issued or issuable upon the exercise of warrants that were sold to those investors identified in this prospectus in our 2000 and 2001 private placements of our common stock and warrants to purchase our common stock.

Information regarding the selling stockholders may change from time to time and any changed information will be set forth in supplements to this prospectus supplement if and when necessary. Unless set forth below, to our knowledge, none of the selling stockholders has, or within the past three years has had, any material relationship with us or any of our predecessors or affiliates.

A selling stockholder may from time to time offer and sell any or all of its securities under this prospectus supplement. Because a selling stockholder is not obligated to sell the shares of our common stock held by it, we cannot estimate the number of shares of our common stock that a selling stockholder will beneficially own after this offering.

 

Name of Selling Stockholder

   Shares Beneficially
Owned Prior to this
Offering
  

Number of Shares
that may be sold

by this Prospectus
Supplement

   Percentage of Shares
Beneficially Owned
After Offering(1)

Lehman Brothers Inc.

   1,025,000    562,500    *

Goldman, Sachs & Co.

   633,380    531,850    *

Goldman Sachs Execution & Clearing, L.P.

   437,500    437,500    *

Deutsche Bank Securities Inc.

   411,300    411,300    *

AIGTI, Inc.

   296,243    296,243    *

Bernard L. Madoff Investment

   250,000    125,000    *

William R. Hough

   238,474    210,526    *

Intel Corporation(2)

   215,000    215,000    *

Bear, Stearns & Co. Inc.(3)

   187,500    187,500    *

JP Morgan Securities Inc.(4)

   165,119    125,050    *

Sunrise Partners Limited

   125,000    125,000    *

D.E. Shaw Valence, L.L.C.

   107,000    6,000    *

Keefe, Bruyette & Woods, Inc.(5)

   94,019    300    *

TD AMERITRADE Online Holdings Corp.

   71,200    24700    *

The Krieger Family Limited Partnership

   58,000    50,000    *

Sandler O’Neill & Partners, L.P.(6)

   46,500    14,125    *

Amaranth LLC

   28,400    300    *

Coastal Capital Markets, LLC

   44,200    22,100    *

Craig A. Smith

   26,000    23,000    *

Hayden R. Fleming & LaDonna M. Fleming Revocable Trust

   20,000    10,000    *

Wien & Malkin Securities Corp.

   19,440    19,440    *

McCarthy & Co.

   19,300    19,300    *

Schonfeld Securities, LLC

   17,900    17,900    *

Valley National Holdings LLC

   16,154    16,154    *

JA Glynn & Co

   14,600    1,200    *

Lipper Analytical Securities Corporation

   13,600    10,600    *

Paulson Investment Company Inc.

   12,400    2,400    *

Scott & Stringfellow, Inc.

   11,875    2,375    *

Great Pacific Fixed Income Securities, Inc.

   11,460    3,730    *

First Analysis Securities Corp.

   11,200    1,000    *

Koonce Securities, Inc.

   11,151    4,600    *

Warren D. Nadel & Company

   11,000    9,000    *

Driehaus Securities Corporation

   11,000    3,000    *

Senvest International LLC

   10,300    10,300    *

Trans American Equities Corporation

   10,300    5,000    *

MHA Financial Corp.

   9,500    3,000    *

Parnassus Investments

   9,500    1,500    *

Mid-Ohio Securities Corp.

   9,400    2,400    *

B. Riley & Co., Inc

   9,300    5,300    *

Delta Equity Services Corporation

   9,000    4,500    *

B-Trade Services LLC

   9,000    3,000    *

Valdes & Moreno, Inc.

   8,600    4,300    *

First State Securities Inc.

   8,500    4,500    *

Franklin Templeton Distributors Inc.

   8,500    1,200    *

Middlegate Securities, Ltd.

   8,500    1,500    *

Rothschild Inc.

   8,210    1,200    *

American Securities Team, Inc.

   8,000    6,000    *

Comprehensive Capital Corporation

   8,000    4,000    *

Marc J. Lane & Company

   8,000    1,500    *

McKinnon & Company, Inc.

   8,000    1,500    *

Larry E Peters

   8,000    1,500    *

Other Stockholders

   952,801    648,164    *

Certain other beneficial owners of common stock or future transferees, pledgees, donees of or from any such holder, if identified as described below (7)(8)

   9,326,138    9,326,138    *

Total

   15,098,464    13,525,195    *

* Less than 1%.

(1) Calculated based on Rule 13d-3(d)(1)(i) of the Securities Exchange Act of 1934, as amended (Exchange Act), using 111,900,966 shares of common stock outstanding (including shares of restricted common stock entitled to vote at the annual meeting) as of May 3, 2006.

(2) One of our directors, Arvind Sodhani, is an officer of Intel Corporation.

(3) Bear, Stearns & Co. Inc. has engaged in, and may in the future engage in, investment banking and other commercial dealings in the ordinary course of business with us, including as a financial advisor or financing source.

(4) JP Morgan Securities Inc. has engaged in, and may in the future engage in, investment banking and other commercial dealings in the ordinary course of business with us, including as a financial advisor or financing source.

(5) Keefe, Bruyette & Woods, Inc. has engaged in, and may in the future engage in, investment banking and other commercial dealings in the ordinary course of business with us, including as a financial advisor or financing source.

(6) One of our directors, Thomas O’Neill, is a founding principal of Sandler O’Neill Partners, L.P. Sandler O’Neill Partners, L.P. has engaged in, and may in the future engage in, investment banking and other commercial dealings in the ordinary course of business with us, including as a financial advisor or financing source.

(7) Selling stockholders may be identified in the table above by us at a later date by filing a prospectus supplement to this prospectus supplement. Such other holders shall not be permitted to sell pursuant to the registration statement unless and until they are listed in the selling stockholders table in a supplement to this prospectus supplement.

(8) Assumes that any selling stockholders or any future pledgees, donees, assignees, transferees or successors of or from such other holders of the shares do not beneficially own any shares of common stock other than the common stock registered hereby.

 

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