The verdict hearing in a trial that has divided Turkish society for the past five years is expected to take place on Monday in Istanbul behind closed doors and amid tight security.
275 defendants including retired generals, journalists and professors have been accused in the Ergenekon trial of organising a network to overthrow the ruling Justice and Development Party.
Violent protests have taken place in recent months in support of those imprisoned and on trial.
In a separate trial last September, a Turkish court sentenced over 300 military officers to prison for attempting to overthrow Prime Minister Tayyip Erdogan almost ten years ago in the so-called Sledgehammer plot.
Since first coming to power in 2002 the Islamist-rooted Justice and Development Party has taken power away from the secularist military.