As part of a legal settlement related to the 2014 Google stock split (steps detailed on our FAQ site at https://www.iclub.com/faq/Home/Article?id=256), Google agreed to pay class C shareholders additional shares or cash if one year after the split the trading price of class C shares were below a certain percentage of the Google class A shares. The threshold for an additional payment was met and Google decided to pay the supplemental amount in additional class C shares.
The information below is based on the information available from the IRS form 8937 filed by Google and available on their web site at https://investor.google.com/pdf/2015_form8937.pdf.
The Stock Split Entry
Go to Transactions > Stock Split or Accounting > Securities > Stock Split depending on the version of the software being used.