Form 13f Holdings Report (13f-hr)

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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

Form 13F

Form 13F COVER PAGE

Report for Calendar Year or Quarter Ended: September 30, 2012

Check here if Amendment [ ]; Amendment Number:

This Amendment (Check only one.): [ ] is a restatement. [ ] adds new holdings entries.

Institutional Investment Manager Filing this Report:

Name: BB Biotech AG Address: Vordergasse 3 Schaffhausen Switzerland CH-8200

Form 13F File Number: 28-6964

The institutional investment manager filing this report and the person by whom it is signed hereby represent that the person signing the report is authorized to submit it, that all information contained herein is true, correct and complete, and that it is understood that all required items, statements, schedules, lists, and tables are considered integral parts of this form.

Person Signing this Report on Behalf of Reporting Manager:

Name: Pascal Schmucki Title: SIGNING AUTHORITY Phone: [phone]

Signature, Place, and Date of Signing: /s/ Pascal Schmucki -------------------------------------------- Schaffhausen, Switzerland, November 5, 2012

Report Type (Check only one.):

[X]13F HOLDINGS REPORT. (Check here if all holdings of this reporting manager
are reported in this report.)

[ ]13F NOTICE. (Check here if no holdings reported are in this report, and all
holdings are reported by other reporting manager(s).)

[ ]13F COMBINATION REPORT. (Check here if a portion of the holdings for this
reporting manager are reported in this report and a portion are reported by
other reporting manager(s).)

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Form 13F SUMMARY PAGE

Report Summary:

Number of Other Included Managers: 3 Form 13F Information Table Entry Total: 19 Form 13F Information Table Value Total: $1,143,784 (thousands)

List of Other Included Managers:

Provide a numbered list of the name(s) and Form 13F file number(s) of all institutional investment managers with respect to which this report is filed, other than the manager filing this report.

No. Form 13F File Number Name 1 28-11193 Biotech Focus N.V. 2 28-11191 Biotech Invest N.V. 3 28-11189 Biotech Target N.V.

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BB BIOTECH AG

FORM 13F INFORMATION TABLE

COLUMN 1 COLUMN 2 COLUMN 3 COLUMN 4 COLUMN 5 COLUMN 6 COLUMN 7 COLUMN 8 ------------------ -------- --------- -------- ------------------ ---------- -------- --------------------- TITLE OF VALUE SHS OR SH/ PUT/ INVESTMENT OTHER VOTING AUTHORITY NAME OF ISSUER CLASS CUSIP (X$1000) PRN AMT PRN CALL DISCRETION MANAGERS SOLE SHARED NONE ------------------ -------- --------- -------- --------- --- ---- ---------- -------- --------- ------ ---- Achillion Pharmaceuticals Inc COM 00448Q201 17,474 1,679,340 SH DEFINED 3 1,679,340 NONE NONE Alexion Pharmaceuticals Inc COM 015351109 51,480 450,000 SH DEFINED 2 450,000 NONE NONE Ariad Pharmaceuticals Inc COM 04033A100 63,937 2,640,939 SH DEFINED 3 2,640,939 NONE NONE Biomarin Pharmaceutical Inc COM 09061G101 39,275 975,545 SH DEFINED 2 975,545 NONE NONE Celgene Corp COM 151020104 208,037 2,723,000 SH DEFINED 2 2,723,000 NONE NONE Dendreon Corp COM 24823Q107 7,333 1,524,500 SH DEFINED 2 1,524,500 NONE NONE Endocyte Inc COM 29269A102 19,442 1,950,093 SH DEFINED 3 1,950,093 NONE NONE Gilead Sciences Inc COM 375558103 139,956 2,110,000 SH DEFINED 1 2,110,000 NONE NONE Halozyme Therapeutics Inc COM 40637H109 41,470 5,500,000 SH DEFINED 3 5,500,000 NONE NONE Idenix Pharmaceuticals Inc COM 45166R204 5,700 1,250,000 SH DEFINED 3 1,250,000 NONE NONE Immunogen Inc COM 45253H101 51,815 3,551,432 SH DEFINED 3 3,551,432 NONE NONE Incyte Corp COM 45337C102 86,615 4,798,597 SH DEFINED 3 4,798,597 NONE NONE Isis Pharmaceuticals Inc COM 464330109 105,438 7,493,800 SH DEFINED 3 7,493,800 NONE NONE Medivation, Inc COM 58501N101 46,511 825,400 SH DEFINED 3 825,400 NONE NONE Onyx Pharmaceuticals Inc COM 683399109 46,179 546,500 SH DEFINED 2 546,500 NONE NONE Optimer Pharmaceuticals Inc COM 68401H104 20,427 1,446,700 SH DEFINED 3 1,446,700 NONE NONE The Medicines Co COM 584688105 40,739 1,578,417 SH DEFINED 2 1,578,417 NONE NONE Theravance Inc COM 88338T104 21,848 843,244 SH DEFINED 3 843,244 NONE NONE Vertex Pharmaceuticals Inc COM 92532F100 130,106 2,327,900 SH DEFINED 3 2,327,900 NONE NONE

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