Astral shares fell $7.85 to $39.15 within minutes of the TSX opening on Friday.
On Thursday, the Canadian Radio-television and Telecommunications Commission ruled that Bell's friendly offer for would have stifled competition.
Bell shares moved lower, losing 72 cents, or almost two per cent, to $42.91. But it was Astral shares that bore the brunt of the damage.
Bell has a number of options, including asking the federal cabinet to overrule the regulator or take their complaint to court. But Astral shareholders are apparently skeptical of the company's ability to generate value or find another suitor, hence the sell-off.
Astral shares are now back to only slightly above where they were before Bell's offer was tabled in March.
More to come