Andre Ward won his biggest fight in June and bestowed the P4P king title cause, well you know, he asked for it during post fight interview. Never defended his crown and choose to retire this month. Is there any shorter reign in the history of pound for pound other than SOG?
Didn't Tony Canzoneri lose one of his titles in his first defense? No, I just checked. Al Singer was the guy who captured his title by first round knockout then lost it by first round knockout to Canzoneri. I knew there was a Canzoneri connection in there somewhere.
If we're going by Ring Magazine, technically speaking, a case can be made for Mike Tyson who was P4P #1 at the conclusion of 1989, before losing to Douglas.
A bit off topic but: Tyson Fury held the IBF title only 10 days before he was stripped of it. Charles Martin only held that belt for almost 3 months.
Ken Norton was given the WBC heavyweight title at a WBC convention in Mexico in March of 1978 and lost it to Larry Holmes in June of 1978. Hell of a way to get a championship belt, and less than 100 days to enjoy it. Of course Leon Spinks ducked him, even Ali stalled on Norton wanting a Superfight in Rio de Janiro but only if he was paid a ridiculous 12 million dollars which he knew wasn't going to happen.