Allos Therapeutics, Inc. Series A Exchangeable Preferred Stock Certificate

Summary

This document certifies ownership of Series A Exchangeable Preferred Stock in Allos Therapeutics, Inc., a Delaware corporation. The certificate is transferable on the company's books by the holder or an authorized attorney upon proper endorsement. It outlines that stockholders can request information about the rights and restrictions of the shares at the company's main office. The certificate also notes that the shares may be held by an affiliate under SEC Rule 144, which may affect transferability.

EX-4.06 6 a2153706zex-4_06.htm EXHIBIT 4.06
QuickLinks -- Click here to rapidly navigate through this document

EXHIBIT 4.06

SEE ADDITIONAL LEGEND ON REVERSE SIDE OF CERTIFICATE

NUMBER
PA-

Incorporated Under the Laws
of the State of Delaware
July 17, 1996

SHARES
* *

ALLOS THERAPEUTICS, INC.
SERIES A EXCHANGEABLE PREFERRED STOCK

THIS CERTIFIES THAT is the record holder of ( ) shares of the Series A Exchangeable Preferred Stock of Allos Therapeutics, Inc. (the "Corporation") transferable only on the books of the Corporation by the holder hereof, in person or by duly authorized attorney, upon surrender of this Certificate properly endorsed or assigned.

A statement of the rights, preferences, privileges and restrictions granted to or imposed upon the respective classes or series of shares of stock of the Corporation, and upon the holders thereof as established by the Restated Certificate of Incorporation, as amended, and the number of shares constituting each series and the designations thereof, may be obtained by any stockholder upon request and without charge at the principal office of the Corporation.

IN WITNESS WHEREOF, the Corporation has caused this Certificate to be signed by its duly authorized officers this day of , 200 .

Secretary

President

EACH

For value Received, hereby sell, assign and transfer unto Shares of the Preferred Stock of the within named Corporation, represented by the within Certificate and do hereby irrevocably constitute and appoint Attorney to transfer the said shares of said Preferred Stock on the books of the said Corporation, pursuant to the provisions of the By-Laws thereof, with full powers of substitution in the premises.

Dated A.D.

In Presence of:

NOTICE: The signature to this assignment must strictly correspond with the name as written upon the face of the Certificate in every particular and without alteration or enlargement or any change whatever.

THE SHARES REPRESENTED BY THIS CERTIFICATE ARE HELD BY A PERSON WHO MAY BE DEEMED TO BE AN AFFILIATE OF THE ISSUER FOR PURPOSES OF RULE 144 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

QuickLinks