Despite manager Lee Clark feeling Birmingham did not recoup anywhere near the true market value of Butland, 19, the Championship club have secured a 20% stake in any profit Stoke make on the player should he be sold on in the future.
Clark believes the Blues should have held out for more than double the fee Stoke eventually paid, having already turned down a £6 million offer from Southampton last summer. However, the financial problems at St Andrews forced Birmingham's owners into accepting a lower fee to ensure they received all the cash in one payment.
It is understood Stoke may have refused to loan Butland back to Birmingham if they had been forced to make a higher offer, while they also would have insisted on staged payments for any fee above the final figure.
Clark was expecting a fire sale at the club on transfer deadline day last week and is hugely grateful for the support of acting chairman Peter Pannu for the work done in keeping his squad together.
"We turned down lots of bids for players. People behind the scenes worked tirelessly. They were the ones on the phones and sending emails all over," Clark said.
"They made sure that players did not have to be sacrificed, when I was led to believe that we were going to have to lose a few players to carry on.
"So the people who made the decisions on those things deserve congratulating, because I was dreading the phone ringing."
Butland signed a four-and-a-half-year deal at Stoke and could well be their No. 1 next season, with Asmir Begovic being linked with a move away from the club in the summer.