Ben Hardy said his brother Josh was given the Fender Telecaster by the band during a 1992 trip to Seattle arranged for them by the Make-a-Wish Foundation. Josh died of a brain tumor three months later.
The coveted guitar was in the basement of the Hardy home in Burlington, which was broken into this fall.
"This is really the only thing I have of his," Ben Hardy, 34, told the Burlington (Vt.) Free Press. "It was a memento from that trip; that was his last trip. The monetary value means nothing. It's Josh's guitar."
The Free Press said the Fender was one of four guitars stolen from the house. A neighbor's home was also broken into about the same time. "We went out there and just met all these bands from the Seattle scene, the Seattle grunge scene," Hardy said.
The trip included a jam session with the Posies and a meeting with members of Nirvana, as well as a trip to the headquarters of Sub Pop Records where they met with Pearl Jam guitarist Mike McCready and his bandmates.