Shares in the Dutch club, in contrast, surged to a record high as it advanced to the semi-final of the lucrative competition for the first time since 1996/97.
Turin-based Juventus lost 1-2 at home to Ajax on Tuesday in the second leg of the quarter finals, resulting in a 2-3 aggregate defeat.
At 0830 GMT, Juventus shares were down 16.15 percent at 1.4150 euros, after trading as low as 1.275 euros. Ajax shares were up 8.45 percent at 1.4500 euros.
Juventus signed Portuguese star Cristiano Ronaldo for a transfer fee of 100 million euros ($113 million) in the hope he would help the club win Europe's elite soccer competition, as he did with Real Madrid for the last three seasons.
Juventus has won the Italian league title seven times in a row, but has never managed to win the "treble" of the domestic league, Italy's cup competition and the Champions League.