Morgan Fox has joined Championship side Sheffield Wednesday for an undisclosed fee.
The full-back, who joined the club's academy at the age of 14, made his debut against the Owls at Hillsbrough in 2014 and went on to play 116 games for the club.
The 23-year old's departure comes shortly after the Addicks announced the signing of left back Lewis Page from West Ham United.
Charlton manager Karl Robinson said: “Every time Morgan Fox stepped on the pitch for Charlton, he gave his all for this club. He’s a hard-working, committed left back and we wish him all the best at Sheffield Wednesday.
“We agreed to let him go once we had a direct replacement for him lined up and I'm very pleased we have been able to sign Lewis on a permanent basis. We have very good depth at left back and we're continuing to focus on building a squad capable of achieving our goal – a place in the top six.”
Charlton CEO Katrien Meire added: “We had a large offer for Morgan on transfer deadline day in the summer which we rejected. However, Sheffield Wednesday came back in for Morgan and he was keen to speak to them.
"We are grateful for Morgan’s great service over the years whether it be for our academy sides or for the Charlton first team.”
Speaking following his departure, Fox said: “I’ve been at Charlton for a long time and it was quite strange collecting my things and leaving Sparrows Lane. I would like to thank everyone at the club for their support throughout my time here. Charlton Athletic will always hold a special place in my heart.”
Fox has made 30 appearances for Charlton this season and was Man of the Match with two assists in the Addicks' 2-0 home victory against Port Vale in November.
He scored one goal during his time as an Addick which came against Queens Park Rangers in a 2-0 win at the start of the 2015/16 season.
Everyone at Charlton wishes him well in his future career.
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