The 19, who include former state security officials and the son of an ex-president, faced charges ranging from money laundering to bribery and blackmail related to a $2 billion "hidden debt" scandal that crashed the nation's economy.
All the accused, who were present in court on Wednesday, have denied any wrongdoing.
In 2016, Mozambique unveiled hefty state-backed borrowing it had previously failed to disclose to parliament or donors like the International Monetary Fund. The scandal prompted the IMF and other donors to cut off support, triggering a currency collapse and debt default.
An independent audit of the debt, ostensibly raised for developing a tuna fishing industry and other projects, found in 2017 that the government had not done enough to explain how funds were spent and that roughly a quarter of the money was unaccounted for.
Judge Efigenio Baptista of the Maputo City Court said reading the 1,388 page judgment was likely to take five days.
"We will be reading the ruling in five days ... We will do our best to make (it) in four days," he said as he began.