According to Post-Dispatch columnist Deb Petterson:

St. Louis Mayor Francis Slay and his wife, Kim, have their house on Oleatha Avenue near Ivanhoe Avenue in the Lindenwood Heights subdivision listed for sale at $419,900. The listing is with the mayor’s brother, Tom Slay, who is with Re/Max Results on Hampton Avenue. The house is a four-bedroom, 2½-bath Cape Cod. The Slays are moving to a new house in the Boulevard Heights neighborhood near Carondelet Park.

UPDATE: Jake Wagman at the Post-Dispatch has made an interesting observation:

The mayor is leaving the 23rd Ward - where his family has deep political roots - and heading into what is, for a lifelong Democrat, enemy territory.

Slay’s new home is in the 12th Ward, represented by Alderman Fred Heitert - the Board of Aldermen’s only Republican.