Being sued by merchants, Mastercard needs cash.
So they sell of some shares and do the administrative thing.
See the document here.
...the Board of Directors of the Company has approved plans for a new ownership and governance structure that will broaden our ownership to include not only customer financial institutions, but also public investors and a foundation to be incorporated in Canada known as The MasterCard Foundation. These plans will also result in a new board of directors with a majority of independent directors. Approval of the proposals to be acted upon at the Special Meeting is necessary for the Company to transition to the new ownership and governance structure.
We believe that the proposed changes will give us a more stable base on which to implement our customer-focused strategy and bring value to our customers’ businesses. We believe this is a positive development for you as both a stockholder and a customer. We intend to continue to leverage our global strength and presence to the benefit of customers while remaining sensitive to regional needs. Through the MasterCard charitable foundation, we also intend to make a significant contribution to the societies in which we operate.