The NSW government will borrow more than $10 billion to inject money into a fund buying stocks and other global financial market assets, in an under-the-radar budget strategy that public finance and credit analysts warn will put taxpayer money at risk.

Market participants believe the innovative financial structuring under state Treasurer Dominic Perrottet is unprecedented in Australia, and rare among governments in the world, because it involves the use of debt to effectively underwrite inflows into the NSW Generations Fund.