Share-based compensation (Tables)

9 Months Ended

Sep. 26, 2020

Share-based Payment Arrangement [Abstract]

Schedule of stock option activity

Summary of movements in options outstanding

	Nine months ended September 26, 2020
	Number of options	Weighted average exercise price $
Outstanding at the beginning of the period:
—Tier I	3,825,855	$	7.07
—Tier II	4,405,340	$	7.01
—Tier III	4,405,340	$	7.01
—Tier IV	4,405,340	$	10.52
—SARs	772,450	$	8.72
—Share options	1,610,485	$	16.69
—Premium-priced options	796,460	$	19.00
	20,221,270	$	9.09
Granted during the period:
—SARs	69,361	$	12.08
—Share options	1,193,114	$	12.55
	1,262,475	$	12.52
Forfeited during the period:
—Tier I	(149,522)	$	9.56
—Tier II	(528,317)	$	7.98
—Tier III	(528,317)	$	7.98
—Tier IV	(528,317)	$	11.96
—Share options	(188,102)	$	16.31
	(1,922,575)	$	10.01
Expired during the period:
—Tier I	(41,961)	$	13.44
—Share options	(60,573)	$	17.21
	(102,534)	$	15.67
Exercised during the period:
—Tier I	(424,726)	$	6.64
	(424,726)	$	6.64
Outstanding at the end of the period:
—Tier I	3,209,646	$	6.93
—Tier II	3,877,023	$	6.88
—Tier III	3,877,023	$	6.88
—Tier IV	3,877,023	$	10.32
—SARs	841,811	$	9.00
—Share options	2,554,924	$	14.77
—Premium-priced options	796,460	$	19.00
	19,033,910	$	9.25
Exercisable at the end of the period	3,400,723	$	8.46
Vested and expected to vest at the end of the period	7,367,055	$	11.16

Schedule of RSU and PRSU activity

Summary of movements in RSUs and PRSUs outstanding

	Nine months ended September 26, 2020
	Number of awards	Weighted average grant date fair value $
Outstanding at the beginning of the period:
—RSUs	718,269	$	16.20
—PRSUs	248,550	$	20.07
	966,819	$	17.20
Granted during the period:
—RSUs	1,206,544	$	11.78
—PRSUs	365,258	$	14.41
	1,571,802	$	12.39
Forfeited during the period:
—RSUs	(87,199)	$	14.78
—PRSUs	(42,158)	$	20.07
	(129,357)	$	16.50
Vested during the period:
—RSUs	(229,606)	$	16.24
	(229,606)	$	16.24
Outstanding at the end of the period:
—RSUs	1,608,008	$	12.96
—PRSUs	571,650	$	16.45
	2,179,658	$	13.88

Schedule of share based compensation valuation techniques

The weighted average fair values and relevant assumptions were as follows:

	Nine months ended
	September 26, 2020			September 28, 2019
Grant date fair value:
—SARs	$	4.59		$	5.88
—Share options	$	4.78		$	5.88
—Premium-priced options	n/a			$	5.65
—RSUs	$	11.78		$	16.28
—PRSUs	$	14.41		$	20.07
Inputs to the model:
—Expected volatility - SARs	37.7		%	31.9		%
—Expected volatility - share options	37.6		%	31.9		%
—Expected volatility - premium-priced options	n/a			31.9		%
—Expected volatility - PRSUs	40.4		%	32.8		%
—Expected option life for SARs	6.0			6.0
—Expected option life for share options	6.0			6.0
—Expected option life for premium-priced options	n/a			7.0
—Risk-free interest rate:
SARs	1.25		%	2.51		%
Share options	1.33		%	2.51		%
Premium-priced options	n/a			2.53		%
PRSUs	1.29		%	2.48		%