The expansion of Affirm's services to Walmart self-checkouts represents a significant partnership that can lead to increased visibility and usage of Affirm's buy now, pay later options. This is likely to be viewed positively by investors, as it suggests growth in Affirm's retail partnerships and potential for increased revenue.

While the primary focus of the news is on Affirm, Walmart stands to benefit from the partnership by offering an additional payment option that could improve customer experience and possibly lead to an increase in self-checkout usage. However, the impact on Walmart's stock may be more muted compared to Affirm, as this is one of many services Walmart offers.