Wyllie netted $16.1 million from the sale of 8 million shares, at $2.01 per share.
That leaves it with a remaining holding of 7.8 million shares.
Wyllie said it has “enjoyed a significant appreciation on its investment as well as a consistent dividend return” since buying into Amcom.
"As a result of a review of our investments, the Wyllie Group has rebalanced its investment portfolio and reduced its exposure to the telecommunications sector,” it said in a statement.
"We are comfortable with our remaining holding in Amcom and are confident of its prospects."
Between December 2006 and August 2007, Wyllie acquired a total of 25.5 million Amcom shares, at an average entry price of 19.5 cents per share.
Amcom has been a quiet achiever since then, consistently lifting profits.
Amcom shares closed down four cents at $2.07.