The City of San Luis emphasizes safety, liquidity, and yield in their investment opportunities. The city invests in the following investments:
- Obligations of the United States or obligations fully guaranteed both as principal and as interest by the United States
- Obligations of the Federal Financing Bank, the Federal Home Loan Bank, the Federal Home Loan Mortgage Corporation, and Fannie Mae
- Deposits at interest or savings certificates of deposit with a local bank and trust companies provided that such deposits or certificates of deposits are made collateral
- Participating shares in a mutual fund for local government investment such as the Local Government Investment Pool (LGIP) managed by the State of Arizona