I'm seeing a small amount in my pending transactions from a retailer I have just made a payment to. What is this transaction?

Some retailers earmark small amounts to that to check that your card is active and valid, this is known as a pre-authorised transaction.

This sometimes happens even if you have not made a payment and have just registered a card for use with a service, like setting up a regular payment or adding it to a digital wallet for a future payment.

The pre-authorised amount will display as a pending transaction for a few days, until it is reversed by the retailer.