Borussia Dortmund CEO Hans-Joachim Watzke told Sunday's AGM the club had emerged battered but afloat from the Covid-19 pandemic with a cost of 151 million euros ($165 million).
The CEO said Dortmund had made "500 million euros in sales" including player transfers in the previous financial year, saying "economically nobody needs to worry about Borussia Dortmund."
But he told club members he suffered sleepless nights at the time.
"we have left the valley of darkness behind us, but it cost us 151 million."
Known for scouting and selling talents on for big profits, Dortmund sold England midfielder Jude Bellingham to Real Madrid in the summer for a fee of up to 130 million euros.
Dortmund had a chance to win their first league title in a decade last season but drew 2-2 at home against mid-table Mainz, to hand the title to rivals Bayern Munich.
Watzke called the result "the most terrible day of my life".
"Something like this can destroy a club or paralyse it for years... but this club is too strong."
The CEO also promised Dortmund would never join a European Super League "no matter what happens."
After 12 league matches this season, Dortmund sit in fourth place and are ten points behind leaders Bayer Leverkusen.
"We were hoping for two or three more points at this stage" Watzke said "but the sky isn't falling."
In the Champions League, Dortmund are first in a group which also includes Paris Saint-Germain, AC Milan and Newcastle.
Dortmund travel to Milan on Tuesday for a clash which is likely to prove crucial in determining who makes the knockout stages of the competition.
"On Tuesday, we have a chance to qualify early with a win" Watzke said.
"I wouldn't have dared to dream of that at the time of the draw."
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