STOCKHOLDERS' EQUITY: (Tables)

3 Months Ended

Mar. 31, 2013

STOCKHOLDERS' EQUITY:

Schedule of activity in treasury stock

Activity in treasury stock in the three-month period ended March 31, 2013 and 2012 is as follows (in millions):

	2013		2012
Southern Copper common shares
Balance as of January 1,	$	729.8	$	734.1
Purchase of shares
Stock dividend	—		(151.4		)
Balance as of March 31,	729.8		582.7
Parent Company (Grupo Mexico) common shares
Balance as of January 1,	189.0		163.7
Other activity, including dividend, interest and currency translation effect	12.4		13.7
Balance as of March 31,	201.4		177.4
Treasury stock balance as of March 31,	$	931.2	$	760.1

Deduction from the amount to be paid to the employee in case of voluntary resignation

If the resignation occurs during:	% Deducted
1st year after the grant date	90	%
2nd year after the grant date	80	%
3rd year after the grant date	70	%
4th year after the grant date	60	%
5th year after the grant date	50	%
6th year after the grant date	40	%
7th year after the grant date	20	%

Deduction from the amount to be paid to the employee in case of involuntary termination

If the termination occurs during:	% Deducted
1st year after the grant date	100	%
2nd year after the grant date	95	%
3rd year after the grant date	90	%
4th year after the grant date	80	%
5th year after the grant date	70	%
6th year after the grant date	60	%
7th year after the grant date	50	%

Employee Stock Purchase Plan

Share based compensation plan

Schedule of stock-based compensation expense and unrecognized compensation expense

The stock based compensation expense for the first quarter 2013 and 2012,  under the Employee Stock Purchase Plan and the unrecognized compensation expense as of March 31, 2013 and 2012 under this plan were as follows (in million):

	2013		2012
Stock based compensation expense	$	0.5	$	0.5
Unrecognized compensation expense	$	3.7	$	5.9

Schedule of stock award activity of the Employee Stock Purchase Plan

	Shares		Unit Weighted AverageGrant Date Fair Value
Outstanding shares at January 1, 2013	6,955,572		$	1.16
Granted	—		—
Exercised	(2,349,157	)	$	1.16
Forfeited	(29,639	)	$	1.16
Outstanding shares at March 31, 2013	4,576,776		$	1.16
Outstanding shares at January 1, 2012	7,270,341		$	1.16
Granted	—		—
Exercised	(36,303	)	$	1.16
Forfeited	(90,204	)	$	1.16
Outstanding shares at March 31, 2012	7,143,834		$	1.16

New Employee Stock Purchase Plan

Share based compensation plan

Schedule of stock-based compensation expense and unrecognized compensation expense

The stock based compensation expense for the first quarter 2013 and 2012, under the New Employee Stock Purchase Plan and the unrecognized compensation expense as of March 31, 2013 and 2012 under this plan were as follows (in million):

	2013		2012
Stock based compensation expense	$	0.1	$	0.1
Unrecognized compensation expense	$	3.0	$	3.7

Schedule of stock award activity of the Employee Stock Purchase Plan

	Shares		Unit Weighted AverageGrant Date Fair Value
Outstanding shares at January 1, 2013	2,944,742		$	2.05
Granted	—		—
Exercised	—		—
Forfeited	(22,638	)	$	2.05
Outstanding shares at March 31, 2013	2,922,104		$	2.05
Outstanding shares at January 1, 2012	3,807,146		$	2.05
Granted	—		—
Exercised	(636,945	)	$	2.05
Forfeited	(51,675	)	$	2.05
Outstanding shares at March 31, 2012	3,118,526		$	2.05