Hulk's agent Teodoro Fonseca told Radio Renascenca that you can never rule out a move.
"Hulk has a contract, he likes FC Porto, but at the moment everything has a question mark," he said.
"We sometimes want a player to stay, but the conditions aren't the best. Sometimes clubs have to give up a right, a player, or a person to keep their structure. People come and go, but the clubs stay.
"Everything is possible in the world of football."