'Canelo' - undefeated in 42 professional bouts - revealed on Twitter that a deal has been struck to unify the two titles at the MGM Grand, Las Vegas, on May 4.
However, ESPN boxing correspondent Dan Rafael has cast doubt on the claim, quoting Golden Boy Promotions CEO Richard Schaefer as saying that nothing has been signed.
He posted on Twitter: "Regarding all the chatter about Canelo-Trout being made, Richard Schaefer told me tonight: 'I don't have a done deal.'"
Trout, who is also unbeaten (26-0) has defended his WBA belt four times, most notably against Miguel Cotto in his last outing in December.
Meanwhile, Alvarez has made five defences since defeating Matthew Hatton for the vacant strap in March 2011.