The practices of ancient Roman finance, while originally rooted in Greek models, evolved in the second century BC with the expansion of Roman monetization. Roman elites engaged in private lending for various purposes, and various banking models arose to serve different lending needs.

Before banks were established in Rome the Romans operated largely within the constraints of the property wealth of their own households. When household wealth was exhausted, the elites in Roman society often extended loans amongst themselves. The value of these loans to the lender was not always derived from interest payments, but rather from the social obligations that were an implication of being a lender. The formation of a societas allowed for coordination of resources among property-owners. Societates were groups who combined their resources to place a bid for a government contract, and then share in the resulting profit or loss.

The publicani (public contractors) were an early incarnation of societates, who bid for the right to collect taxes from the Roman provinces. Senators were not allowed to engage in trade, so it fell to the knights (equites) to bid on these contracts issued by the censors every five years. Banks were established in Rome, modelled upon their Greek counterparts, and introduced formalized financial intermediation. Livy is the first writer to acknowledge the rise of formal Roman banks in 310 BC.

Ancient Roman banks operated under private law, which did not have clear guidance on how to decide cases concerning financial matters. This forced Roman banks to operate entirely on their word and character. Bankers congregated around the arch of Janus to conduct their business and despite their informal location, were clearly professional in their dealings.

Up until the dawn of the Roman Empire, it was common for loans to be negotiated as oral contracts. In the early Empire, lenders and borrowers began to adopt the usage of a chirographum (“handwritten record”) to record these contracts and use them for evidence of the agreed terms. One copy of the contract was presented on the exterior of the chirographum, while a second copy was kept sealed within two waxed tablets of the document, in the presence of a witness. Informal methods of maintaining records of loans made and received existed, as well as formal incarnations adopted by frequent lenders. These serial lenders used a kalendarium to document the loans that they issued to assist in tabulating interest accrued at the beginning of each month (Kalends).

Parties to contracts were supposed to be Roman citizens, but there is evidence of this boundary being broken. Loans to citizens were also originated from public or governmental positions. For example, the Temple of Apollo is believed to have engaged in secured loans with citizens’ homes being used as collateral. Loans were more rarely extended to citizens from the government, as in the case of Tiberius who allowed for three-year, interest-free loans to be issued to senators in order to avert a looming credit crisis.

There is sufficient evidence of deferred payments and financing arrangements to be negotiated for large purchases. Deferred payments were used in the auction of wine or oil that was "on the tree", not yet harvested or produced, requiring payment from the winning bidder, long after the auction had ended. Roman peasants who needed money to pay their taxes used an inverted form of this process, by selling the right to a portion of their harvest in the future, in exchange for cash in the present. The sulpicii arose as professional bankers in the first century AD. Among other forms of financial intermediation, they offered financing for speculators in grain markets.

For centuries the monetary affairs of the Roman Republic had rested in the hands of the Senate. These elite liked to present themselves as steady and fiscally conservative, but as the 19th-century historian of Rome Wilhelm Ihne remarked: