The Ministry of Finance said in a statement that 37 out of the 128 companies have been divested as of July, meaning 91 remain to be sold off in five months.
The Covid-19 pandemic has impacted all areas of the economy, resulting in the delay, the ministry said.
Companies that have been identified for initial public offerings but are yet to complete their valuation include mobile operator MobiFone, lender Agribank, and mining firm Vinacomin.
The 128 companies are part of 177 the government has identified for privatization.