Umbro
Kit sponsor from the season 1989-1990 untill 1999-2000. In January 1999 Ajax closed a new contract with Umbro continuing their co-operation till 2003. But in April 1999 Umbro was taken over by Doughty Hanson & Co and this company didn't agree with the closed contract. Ajax sued Umbro for this resulting in the fact that the contract between Ajax and Umbro wasn't legitimate anymore meaning that after 11 years Umbro wouldn't be the kit manufacturer for Ajax anymore. Looking for a new supplier Ajax came in contact with Adidas and on the 5th of July 2000 a 3-year contract was signed.
In 1991 Ajax signed a new sponsoring-contract with ABN AMRO (Dutch bank) so after 9 years of TDK-sponsoring the name of ABN AMRO was visible on the Ajax shirt. Remarkable was that the characters of ABN AMRO were placed vertically on the shirt.
In the season 1997-1998 each Ajax player got his own number on the back of their shirt. A year later the KNVB made this a rule for every Dutch football club.