REG-Calamos Advisors LLC: Rule 8.3 - Xstrata Plc

FORM 8.3

DEALINGS BY PERSONS WITH INTERESTS IN SECURITIES REPRESENTING 1% OR MORE

(Rule 8.3 of the Takeover Code)

1. KEY INFORMATION

Name of person dealing (Note 1) Calamos Advisors LLC, as investment manager

Company dealt in Xstrata Plc

Class of relevant security to 4% Convertible Notes due 2017
which the dealings being
disclosed relate (Note 2)

Dates of dealing 9 July 2009

2. INTERESTS, SHORT POSITIONS AND RIGHTS TO SUBSCRIBE

(a) Interests and short positions (following dealing) in the class of relevant
security dealt in (Note 3)

Long Short

Number (%) Number (%)

(1) Relevant securities 1,500,000.00* 3.87

(2) Derivatives (other than
options)

(3) Options and agreements to
purchase/sell

Total 14,500,000.00* 3.87

* Represents full face value

(b) Interests and short positions in relevant securities of the company, other
than the class dealt in (Note 3)

Class of relevant security: Long Short

Number (%) Number (%)

(1) Relevant securities

(2) Derivatives (other than
options)

(3) Options and agreements to
purchase/sell

Total

(c) Rights to subscribe (Note 3)

Class of relevant security: Details

3. DEALINGS (Note 4)

(a) Purchases and sales

Purchase/sale Number of securities Price per unit (Note 5)

9 July 2009 1,500,000.00 103.375

(b) Derivatives transactions (other than options)

Product name, Long/short (Note Number of securities Price per unit (Note
6) (Note 7) 5)
e.g. CFD

(c) Options transactions in respect of existing securities

(i) Writing, selling, purchasing or varying

Product name, Writing, Number of Exercise Type, e.g. Expiry Option
selling, securities to American, money
e.g. call purchasing, which the price European date
option varying option etc. paid/
etc. relates (Note received
7) per unit
(Note 5)

(ii) Exercising

Product name, e.g. call Number of securities Exercise price per unit
option (Note 5)

(d) Other dealings (including new securities) (Note 4)

Nature of transaction Details Price per unit (if
(Note 8) applicable) (Note 5)

4. OTHER INFORMATION

Agreements, arrangements or understandings relating to options or derivatives

Full details of any agreement, arrangement or understanding between the person
disclosing and any other person relating to the voting rights of any relevant
securities under any option referred to on this form or relating to the voting
rights or future acquisition or disposal of any relevant securities to which
any derivative referred to on this form is referenced. If none, this should be
stated.

None

Is a Supplemental Form 8 attached? (Note 9) NO

Date of disclosure 9 July 2009

Contact name Stathy Darcy, VP, Deputy General
Counsel-Mutual Funds, Calamos
Advisors LLC

Telephone number +1 630 245 1046

If a connected EFM, name of offeree/offeror
with which connected

If a connected EFM, state nature of
connection (Note 10)

Notes

The Notes on Form 8.3 can be viewed on the Takeover Panel's website at
www.thetakeoverpanel.org.uk

END