Stoke have been handed a £1.5m boost after Manchester United sold Ben Foster to Birmingham for £6m.
The Potters inserted the clause when Foster left the Britannia Stadium for Old Trafford in 2005, with City receiving 30% of any profit on the £1m paid by the Red Devils up front.
WIth other clauses being met aswell City have banked around £3m from the deal, not bad for a keeper signed for a nominal fee and who never played a competitive game for the club.