The newspaper said Phelps has not announced his purchase of a loft in the up-and-coming Canton neighborhood. But neighbors say Phelps sightings are frequent, and he reportedly has patronized neighborhood watering holes.
An anonymous trust purchased the property for $1.3 million cash in February, the Sun said. The trust's mailing address happens to be that of Octagon Sports Management, where Phelps' agent works.
In 2007, Phelps bought a place in the Fells Point neighborhood for $1.69 million. It was sold in July for $1.25 million.
The property consists of two industrial buildings dating from the late 19th and early 20th centuries. Andrew McQuaid, a developer who owned the property for eight years, renovated it and then put it on the market in 2011.
The Canton neighborhood borders part of Baltimore's Outer Harbor. A century ago, it was known for its factories and the houses of blue-collar workers, but in recent years new townhouses have gone up and old buildings have been renovated into waterfront properties.
Phelps, the son of a Maryland state trooper, grew up in Towson, just north of Baltimore. He was on the U.S. swim team for the 2004, 2008 and 2012 Summer Olympics, winning a record total of 22 medals, 18 of them gold, which is also a record.