 Shares of Affirm Holdings Inc. AFRM, -3.66 were up more than 3 in premarket trading Thursday after the company announced that it would launch a buy-now-pay-later option on Amazon.com Inc.s AMZN, -2.99 site in Canada. The company already has a relationship with Amazon in the U.S. Affirm noted in a Thursday press release that eligible Canadian Amazon shoppers will be able to split purchases into monthly installments on purchases of 50 or more. 