When does a listing expire?

A listing will expire at the end of the day of its expiration date.  

For example, if your listing has an Expiration Date of June 15th, the listing will still be Active throughout the day of June 15th and will automatically be changed to Expired right after midnight, when the calendar day changes from the 15th to the 16th.

The only exception to this is Under Contract listings- these listings will not expire, even after passing their expiration date.