The Company is authorized to issue an unlimited number of Common Shares, an unlimited number of First Preferred Shares, and an unlimited number of Second Preferred Shares. At December 31, 2019, no First or Second Preferred Shares had been issued.

The following table summarizes information related to Common Share balances as at December 31:



(number of shares in millions)	2019		2018		2017
Share capital, January 1	140.5		144.9		146.3
CP Common Shares repurchased	(3.8	)	(4.6	)	(1.9	)
Shares issued under stock option plan	0.3		0.2		0.5
Share capital, December 31	137.0		140.5		144.9

The change in the “Share capital” balance includes $7 million of stock-based compensation transferred from “Additional paid-in capital” (2018 – $12 million; 2017 – $12 million).

On May 10, 2017, the Company announced a normal course issuer bid ("NCIB"), commencing May 15, 2017, to purchase up to 4.38 million Common Shares in the open market for cancellation on or before May 14, 2018. The Company completed this NCIB on May 10, 2018.

On October 19, 2018, the Company announced a NCIB, commencing October 24, 2018, to purchase up to 5.68 million Common Shares for cancellation on or before October 23, 2019. The Company completed this NCIB on October 23, 2019.

On December 17, 2019, the Company announced a new NCIB, commencing December 20, 2019, to purchase up to 4.80 million Common Shares for cancellation on or before December 19, 2020. As at December 31, 2019, the Company had purchased 0.30 million Common Shares for $100 million under this NCIB program.

All purchases were made in accordance with the respective NCIB at prevalent market prices plus brokerage fees, or such other prices that were permitted by the Toronto Stock Exchange, with consideration allocated to share capital up to the average carrying amount of the shares and any excess allocated to "Retained earnings".

The following table provides the activities under the share repurchase programs for each of the years ended December 31:



	2019		2018		2017
Number of Common Shares repurchased⁽¹⁾	3,794,149		4,683,162		1,888,100
Weighted-average price per share⁽²⁾	$	300.65	$	240.68	$	201.53
Amount of repurchase (in millions)⁽²⁾	$	1,141	$	1,127	$	381

⁽¹⁾Includes shares repurchased but not yet cancelled at year end.