Calmund started working at
Bayer 04 Leverkusen in 1976 as a youth leader and announcer. Then, until 1988, he was a
board member. Afterwards he was manager of the professional football department. Calmund became Managing Director of Bayer Leverkusen in 1999. Leverkusen's greatest success during Calmund's tenure was winning the
UEFA Cup in 1988 and the
German Cup in 1993. In addition, Leverkusen were runners-up four (
1997,
1999,
2000,
2002) times for the Meisterschaft, as well as once for the
Champions League final.(2002). Especially in the
2001/2002 season, when Leverkusen finished second in the Bundesliga, DFB Cup and Champions League, earned the club the nickname "
Vizekusen". Calmund was one of the first to realize the possibility of recruiting top players in East Germany as soon as the
Berlin Wall fell on 9 November 1989. He arranged the recruitment of
Andreas Thom from
BFC Dynamo. The transfer was made public on 16 December 1989. Andreas Thom became the first player in the
DDR-Oberliga to be transferred to the Bundesliga. Calmund soon also arranged the signing of
Ulf Kirsten from
SG Dynamo Dresden. He has said: "The GDR had top class youth academies with full-time coaches, stuff that we in the West could only dream of in the 1980s". Calmund is considered a prime mover in mining East Germany for talent during the period known as
Die Wende. Calmund was also responsible for the signings of
Bernd Schuster,
Michael Ballack, and
Rudi Völler. Additionally, he was able to win the Brazilians
Paulo Sérgio,
Jorginho,
Emerson,
Zé Roberto,
Lúcio and
Juan, as well as Bulgarian
Dimitar Berbatov for the club. On 8 June 2004, Calmund announced – for health reasons – his resignation as
CEO of Bayer 04 Leverkusen for 30 June 2004. It became public in March 2006 that Calmund had been laid off by the club. The reason being an unexplained cash payment of €580,000 to the
Bielefeld player's agent,
Volker Graul, allegedly to purchase two Croatian players who never committed. In addition, Calmund claims to have paid Graul, at the request of Bayer Leverkusen, €350,000 from his private assets. The Cologne public prosecutor held proceedings against Calmund for a breach of trust, but the matter was settled with the payment of a €30,000 fine . ==Other activities==