DISPLAYING A SPONSORED CONTENT ITEM IN CONJUNCTION WITH MESSAGE THREADS BASED ON LIKELIHOOD OF MESSAGE THREAD SELECTION

A messaging application provides a user interface displaying a user's threads, where each thread includes at least one message between the user and another user. Via the user interface, the user may select a thread to access messages in the thread or to add one or more messages to the thread. The messaging application also displays a sponsored content item along with the threads, but displays the sponsored content item below threads having unread messages to avoid reducing engagement with threads the user is likely to select. In some embodiments, the messaging application predicts a probability that displaying the sponsored content item above a thread including an unread message thread will cause the user not to engage with the thread and displays the sponsored content item above the thread including the unread message if the predicted probability is below a threshold.